diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 3f91485..be68631 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -33,7 +33,7 @@ repos:
 
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.15.6
+  rev: v0.16.1
   hooks:
     - id: ruff
       args: [--fix, --exit-non-zero-on-fix]
diff --git a/setup.py b/setup.py
index cd7a07d..ddc8af3 100644
--- a/setup.py
+++ b/setup.py
@@ -10,7 +10,7 @@
 if __name__ == "__main__":
     try:
         setup(use_scm_version={"version_scheme": "no-guess-dev"})
-    except:  # noqa
+    except:
         print(
             "\n\nAn error occurred while building the project, "
             "please ensure you have the most updated version of setuptools, "
diff --git a/src/summarizedexperiment/RangedSummarizedExperiment.py b/src/summarizedexperiment/RangedSummarizedExperiment.py
index 3414ea5..b42271e 100644
--- a/src/summarizedexperiment/RangedSummarizedExperiment.py
+++ b/src/summarizedexperiment/RangedSummarizedExperiment.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
-from typing import Any, Dict, List, Literal, Optional, Sequence, Union
+from collections.abc import Sequence
+from typing import Any, Literal, Union
 from warnings import warn
 
 import biocframe
@@ -92,13 +93,13 @@ class RangedSummarizedExperiment(SummarizedExperiment):
 
     def __init__(
         self,
-        assays: Dict[str, Any] = None,
-        row_ranges: Optional[GRangesOrGRangesList] = None,
-        row_data: Optional[biocframe.BiocFrame] = None,
-        column_data: Optional[biocframe.BiocFrame] = None,
-        row_names: Optional[List[str]] = None,
-        column_names: Optional[List[str]] = None,
-        metadata: Optional[Union[Dict[str, Any], ut.NamedList]] = None,
+        assays: dict[str, Any] = None,
+        row_ranges: GRangesOrGRangesList | None = None,
+        row_data: biocframe.BiocFrame | None = None,
+        column_data: biocframe.BiocFrame | None = None,
+        row_names: list[str] | None = None,
+        column_names: list[str] | None = None,
+        metadata: dict[str, Any] | ut.NamedList | None = None,
         _validate: bool = True,
     ) -> None:
         """Initialize a `RangedSummarizedExperiment` (RSE) object.
@@ -274,7 +275,7 @@ def __str__(self) -> str:
         )
         output += f"column_names({0 if self._column_names is None else len(self._column_names)}): {' ' if self._column_names is None else ut.print_truncated_list(self._column_names)}\n"
 
-        output += f"metadata({str(len(self.metadata))}): {ut.print_truncated_list(list(self.metadata.keys()), sep=' ', include_brackets=False, transform=lambda y: y)}"
+        output += f"metadata({len(self.metadata)!s}): {ut.print_truncated_list(list(self.metadata.keys()), sep=' ', include_brackets=False, transform=lambda y: y)}"
 
         return output
 
@@ -291,7 +292,7 @@ def get_row_ranges(self) -> GRangesOrGRangesList:
         return self._row_ranges
 
     def set_row_ranges(
-        self, row_ranges: Optional[GRangesOrGRangesList], in_place: bool = False
+        self, row_ranges: GRangesOrGRangesList | None, in_place: bool = False
     ) -> RangedSummarizedExperiment:
         """Set new genomic features.
 
@@ -351,7 +352,7 @@ def start(self) -> np.ndarray:
         return self.row_ranges.start
 
     @property
-    def seqnames(self) -> List[str]:
+    def seqnames(self) -> list[str]:
         """Get sequence or chromosome names.
 
         Returns:
@@ -392,12 +393,9 @@ def seq_info(self) -> SeqInfo:
 
     # rest of them are inherited from BaseSE.
 
-    def _normalize_row_slice(self, rows: Union[str, int, bool, Sequence]):
+    def _normalize_row_slice(self, rows: str | int | bool | Sequence):
 
-        if isinstance(rows, (GenomicRanges, CompressedGenomicRangesList)):
-            hits = self.row_ranges.find_overlaps(query=rows)
-            rows = hits.get_column("self_hits")
-        elif hasattr(rows, "find_overlaps"):
+        if isinstance(rows, (GenomicRanges, CompressedGenomicRangesList)) or hasattr(rows, "find_overlaps"):
             hits = self.row_ranges.find_overlaps(query=rows)
             rows = hits.get_column("self_hits")
 
@@ -405,8 +403,8 @@ def _normalize_row_slice(self, rows: Union[str, int, bool, Sequence]):
 
     def get_slice(
         self,
-        rows: Optional[Union[str, int, bool, Sequence]],
-        columns: Optional[Union[str, int, bool, Sequence]],
+        rows: str | int | bool | Sequence | None,
+        columns: str | int | bool | Sequence | None,
     ) -> RangedSummarizedExperiment:
         """Alias for :py:attr:`~__getitem__`, for back-compatibility."""
 
@@ -431,7 +429,7 @@ def get_slice(
     ######>> range ops <<#######
     ############################
 
-    def coverage(self, shift: int = 0, width: Optional[int] = None, weight: int = 1) -> Dict[str, np.ndarray]:
+    def coverage(self, shift: int = 0, width: int | None = None, weight: int = 1) -> dict[str, np.ndarray]:
         """Calculate coverage for each chromosome.
 
         Args:
@@ -456,7 +454,7 @@ def nearest(
         query: GRangesOrRangeSE,
         select: Literal["all", "arbitrary"] = "all",
         ignore_strand: bool = False,
-    ) -> Optional[List[Optional[int]]]:
+    ) -> list[int | None] | None:
         """Search nearest positions both upstream and downstream that overlap with each range in ``query``.
 
         Args:
@@ -496,7 +494,7 @@ def precede(
         query: GRangesOrRangeSE,
         select: Literal["all", "arbitrary"] = "all",
         ignore_strand: bool = False,
-    ) -> Optional[List[Optional[int]]]:
+    ) -> list[int | None] | None:
         """Search nearest positions only downstream that overlap with each range in ``query``.
 
         Args:
@@ -536,7 +534,7 @@ def follow(
         query: GRangesOrRangeSE,
         select: Literal["all", "arbitrary"] = "all",
         ignore_strand: bool = False,
-    ) -> Optional[List[Optional[int]]]:
+    ) -> list[int | None] | None:
         """Search nearest positions only upstream that overlap with each range in ``query``.
 
         Args:
@@ -617,7 +615,7 @@ def flank(
 
     def resize(
         self,
-        width: Union[int, List[int], np.ndarray],
+        width: int | list[int] | np.ndarray,
         fix: Literal["start", "end", "center"] = "start",
         ignore_strand: bool = False,
         in_place: bool = False,
@@ -654,7 +652,7 @@ def resize(
         output._row_ranges = new_ranges
         return output
 
-    def shift(self, shift: Union[int, List[int], np.ndarray] = 0, in_place: bool = False) -> RangedSummarizedExperiment:
+    def shift(self, shift: int | list[int] | np.ndarray = 0, in_place: bool = False) -> RangedSummarizedExperiment:
         """Shift all intervals.
 
         ``shift`` may be be negative.
@@ -708,8 +706,8 @@ def promoters(
 
     def restrict(
         self,
-        start: Optional[Union[int, List[int], np.ndarray]] = None,
-        end: Optional[Union[int, List[int], np.ndarray]] = None,
+        start: int | list[int] | np.ndarray | None = None,
+        end: int | list[int] | np.ndarray | None = None,
         keep_all_ranges: bool = False,
         in_place: bool = False,
     ) -> RangedSummarizedExperiment:
@@ -742,9 +740,9 @@ def restrict(
 
     def narrow(
         self,
-        start: Optional[Union[int, List[int], np.ndarray]] = None,
-        width: Optional[Union[int, List[int], np.ndarray]] = None,
-        end: Optional[Union[int, List[int], np.ndarray]] = None,
+        start: int | list[int] | np.ndarray | None = None,
+        width: int | list[int] | np.ndarray | None = None,
+        end: int | list[int] | np.ndarray | None = None,
         in_place: bool = False,
     ) -> RangedSummarizedExperiment:
         """Narrow genomic positions by provided ``start``, ``width`` and ``end`` parameters.
diff --git a/src/summarizedexperiment/SummarizedExperiment.py b/src/summarizedexperiment/SummarizedExperiment.py
index c841c55..3a6ac61 100644
--- a/src/summarizedexperiment/SummarizedExperiment.py
+++ b/src/summarizedexperiment/SummarizedExperiment.py
@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from typing import Any, Dict, List, Optional, Union
+from typing import Any
 from warnings import warn
 
 import biocframe
@@ -30,12 +30,12 @@ class SummarizedExperiment(BaseSE):
 
     def __init__(
         self,
-        assays: Dict[str, Any] = None,
-        row_data: Optional[biocframe.BiocFrame] = None,
-        column_data: Optional[biocframe.BiocFrame] = None,
-        row_names: Optional[List[str]] = None,
-        column_names: Optional[List[str]] = None,
-        metadata: Optional[Union[Dict[str, Any], ut.NamedList]] = None,
+        assays: dict[str, Any] = None,
+        row_data: biocframe.BiocFrame | None = None,
+        column_data: biocframe.BiocFrame | None = None,
+        row_names: list[str] | None = None,
+        column_names: list[str] | None = None,
+        metadata: dict[str, Any] | ut.NamedList | None = None,
         _validate: bool = True,
     ) -> None:
         """Initialize a Summarized Experiment (SE).
diff --git a/src/summarizedexperiment/__init__.py b/src/summarizedexperiment/__init__.py
index 728b695..ed383ef 100644
--- a/src/summarizedexperiment/__init__.py
+++ b/src/summarizedexperiment/__init__.py
@@ -15,5 +15,5 @@
 finally:
     del version, PackageNotFoundError
 
-from .SummarizedExperiment import SummarizedExperiment
 from .RangedSummarizedExperiment import RangedSummarizedExperiment
+from .SummarizedExperiment import SummarizedExperiment
diff --git a/src/summarizedexperiment/base.py b/src/summarizedexperiment/base.py
index fcb2e34..9f6056f 100644
--- a/src/summarizedexperiment/base.py
+++ b/src/summarizedexperiment/base.py
@@ -2,7 +2,8 @@
 
 import warnings
 from collections import OrderedDict, namedtuple
-from typing import Any, Dict, List, Optional, Sequence, Tuple, Union
+from collections.abc import Sequence
+from typing import Any
 from warnings import warn
 
 import biocframe
@@ -131,12 +132,12 @@ class BaseSE(ut.BiocObject):
 
     def __init__(
         self,
-        assays: Dict[str, Any] = None,
-        row_data: Optional[biocframe.BiocFrame] = None,
-        column_data: Optional[biocframe.BiocFrame] = None,
-        row_names: Optional[List[str]] = None,
-        column_names: Optional[List[str]] = None,
-        metadata: Optional[Union[Dict[str, Any], ut.NamedList]] = None,
+        assays: dict[str, Any] = None,
+        row_data: biocframe.BiocFrame | None = None,
+        column_data: biocframe.BiocFrame | None = None,
+        row_names: list[str] | None = None,
+        column_names: list[str] | None = None,
+        metadata: dict[str, Any] | ut.NamedList | None = None,
         _validate: bool = True,
     ) -> None:
         """Initialize an instance of ``BaseSE``.
@@ -287,7 +288,7 @@ def __len__(self) -> int:
         return self.shape[0]
 
     @property
-    def shape(self) -> Tuple[int, int]:
+    def shape(self) -> tuple[int, int]:
         """Get shape of the experiment.
 
         Returns:
@@ -298,7 +299,7 @@ def shape(self) -> Tuple[int, int]:
         return self._shape
 
     @property
-    def dims(self) -> Tuple[int, int]:
+    def dims(self) -> tuple[int, int]:
         """Alias to :py:attr:`~summarizedexperiment.BaseSE.BaseSE.shape`.
 
         Returns:
@@ -356,7 +357,7 @@ def __str__(self) -> str:
         )
         output += f"column_names({0 if self._column_names is None else len(self._column_names)}): {' ' if self._column_names is None else ut.print_truncated_list(self._column_names)}\n"
 
-        output += f"metadata({str(len(self.metadata))}): {ut.print_truncated_list(list(self.metadata.keys()), sep=' ', include_brackets=False, transform=lambda y: y)}"
+        output += f"metadata({len(self.metadata)!s}): {ut.print_truncated_list(list(self.metadata.keys()), sep=' ', include_brackets=False, transform=lambda y: y)}"
 
         return output
 
@@ -364,7 +365,7 @@ def __str__(self) -> str:
     ######>> assays <<######
     ########################
 
-    def get_assays(self) -> Dict[str, Any]:
+    def get_assays(self) -> dict[str, Any]:
         """Access assays/experimental data.
 
         Returns:
@@ -373,7 +374,7 @@ def get_assays(self) -> Dict[str, Any]:
         """
         return self._assays
 
-    def set_assays(self, assays: Dict[str, Any], in_place: bool = False) -> BaseSE:
+    def set_assays(self, assays: dict[str, Any], in_place: bool = False) -> BaseSE:
         """Set new experiment data (assays).
 
         Args:
@@ -394,12 +395,12 @@ def set_assays(self, assays: Dict[str, Any], in_place: bool = False) -> BaseSE:
         return output
 
     @property
-    def assays(self) -> Dict[str, Any]:
+    def assays(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_assays`."""
         return self.get_assays()
 
     @assays.setter
-    def assays(self, assays: Dict[str, Any]):
+    def assays(self, assays: dict[str, Any]):
         """Alias for :py:meth:`~set_assays` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -436,7 +437,7 @@ def get_row_data(self, replace_row_names: bool = True) -> biocframe.BiocFrame:
 
     def set_row_data(
         self,
-        rows: Optional[biocframe.BiocFrame],
+        rows: biocframe.BiocFrame | None,
         replace_row_names: bool = False,
         in_place: bool = False,
     ) -> BaseSE:
@@ -473,12 +474,12 @@ def set_row_data(
         return output
 
     @property
-    def rowdata(self) -> Dict[str, Any]:
+    def rowdata(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_rowdata`."""
         return self.get_row_data()
 
     @rowdata.setter
-    def rowdata(self, rows: Optional[biocframe.BiocFrame]):
+    def rowdata(self, rows: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_rowdata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -490,12 +491,12 @@ def rowdata(self, rows: Optional[biocframe.BiocFrame]):
         self.set_row_data(rows, in_place=True)
 
     @property
-    def row_data(self) -> Dict[str, Any]:
+    def row_data(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_rowdata`."""
         return self.get_row_data()
 
     @row_data.setter
-    def row_data(self, rows: Optional[biocframe.BiocFrame]):
+    def row_data(self, rows: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_rowdata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -532,7 +533,7 @@ def get_column_data(self, replace_row_names: bool = True) -> biocframe.BiocFrame
 
     def set_column_data(
         self,
-        cols: Optional[biocframe.BiocFrame],
+        cols: biocframe.BiocFrame | None,
         replace_column_names: bool = False,
         in_place: bool = False,
     ) -> BaseSE:
@@ -569,12 +570,12 @@ def set_column_data(
         return output
 
     @property
-    def columndata(self) -> Dict[str, Any]:
+    def columndata(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_coldata`."""
         return self.get_column_data()
 
     @columndata.setter
-    def columndata(self, cols: Optional[biocframe.BiocFrame]):
+    def columndata(self, cols: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_coldata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -586,12 +587,12 @@ def columndata(self, cols: Optional[biocframe.BiocFrame]):
         self.set_column_data(cols, in_place=True)
 
     @property
-    def coldata(self) -> Dict[str, Any]:
+    def coldata(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_coldata`."""
         return self.get_column_data()
 
     @coldata.setter
-    def coldata(self, cols: Optional[biocframe.BiocFrame]):
+    def coldata(self, cols: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_coldata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -603,12 +604,12 @@ def coldata(self, cols: Optional[biocframe.BiocFrame]):
         self.set_column_data(cols, in_place=True)
 
     @property
-    def column_data(self) -> Dict[str, Any]:
+    def column_data(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_coldata`."""
         return self.get_column_data()
 
     @column_data.setter
-    def column_data(self, cols: Optional[biocframe.BiocFrame]):
+    def column_data(self, cols: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_coldata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -620,12 +621,12 @@ def column_data(self, cols: Optional[biocframe.BiocFrame]):
         self.set_column_data(cols, in_place=True)
 
     @property
-    def col_data(self) -> Dict[str, Any]:
+    def col_data(self) -> dict[str, Any]:
         """Alias for :py:meth:`~get_coldata`."""
         return self.get_column_data()
 
     @col_data.setter
-    def col_data(self, cols: Optional[biocframe.BiocFrame]):
+    def col_data(self, cols: biocframe.BiocFrame | None):
         """Alias for :py:meth:`~set_coldata` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -640,14 +641,14 @@ def col_data(self, cols: Optional[biocframe.BiocFrame]):
     ######>> row names <<#####
     ##########################
 
-    def get_row_names(self) -> Optional[ut.Names]:
+    def get_row_names(self) -> ut.Names | None:
         """
         Returns:
             List of row names, or None if no row names are available.
         """
         return self._row_names
 
-    def set_row_names(self, names: Optional[List[str]], in_place: bool = False) -> BaseSE:
+    def set_row_names(self, names: list[str] | None, in_place: bool = False) -> BaseSE:
         """Set new row names.
 
         Args:
@@ -673,12 +674,12 @@ def set_row_names(self, names: Optional[List[str]], in_place: bool = False) -> B
         return output
 
     @property
-    def rownames(self) -> Optional[ut.Names]:
+    def rownames(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_row_names`, provided for back-compatibility."""
         return self.get_row_names()
 
     @rownames.setter
-    def rownames(self, names: Optional[List[str]]):
+    def rownames(self, names: list[str] | None):
         """Alias for :py:meth:`~set_row_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -690,12 +691,12 @@ def rownames(self, names: Optional[List[str]]):
         self.set_row_names(names, in_place=True)
 
     @property
-    def row_names(self) -> Optional[ut.Names]:
+    def row_names(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_row_names`, provided for back-compatibility."""
         return self.get_row_names()
 
     @row_names.setter
-    def row_names(self, names: Optional[List[str]]):
+    def row_names(self, names: list[str] | None):
         """Alias for :py:meth:`~set_row_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -710,14 +711,14 @@ def row_names(self, names: Optional[List[str]]):
     ######>> column names <<#####
     #############################
 
-    def get_column_names(self) -> Optional[ut.Names]:
+    def get_column_names(self) -> ut.Names | None:
         """
         Returns:
             List of column names, or None if no column names are available.
         """
         return self._column_names
 
-    def set_column_names(self, names: Optional[List[str]], in_place: bool = False) -> BaseSE:
+    def set_column_names(self, names: list[str] | None, in_place: bool = False) -> BaseSE:
         """Set new column names.
 
         Args:
@@ -743,12 +744,12 @@ def set_column_names(self, names: Optional[List[str]], in_place: bool = False) -
         return output
 
     @property
-    def columnnames(self) -> Optional[ut.Names]:
+    def columnnames(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_column_names`, provided for back-compatibility."""
         return self.get_column_names()
 
     @columnnames.setter
-    def columnnames(self, names: Optional[List[str]]):
+    def columnnames(self, names: list[str] | None):
         """Alias for :py:meth:`~set_column_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -760,12 +761,12 @@ def columnnames(self, names: Optional[List[str]]):
         self.set_column_names(names, in_place=True)
 
     @property
-    def colnames(self) -> Optional[ut.Names]:
+    def colnames(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_column_names`, provided for back-compatibility."""
         return self.get_column_names()
 
     @colnames.setter
-    def colnames(self, names: Optional[List[str]]):
+    def colnames(self, names: list[str] | None):
         """Alias for :py:meth:`~set_column_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -777,12 +778,12 @@ def colnames(self, names: Optional[List[str]]):
         self.set_column_names(names, in_place=True)
 
     @property
-    def col_names(self) -> Optional[ut.Names]:
+    def col_names(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_column_names`, provided for back-compatibility."""
         return self.get_column_names()
 
     @col_names.setter
-    def col_names(self, names: Optional[List[str]]):
+    def col_names(self, names: list[str] | None):
         """Alias for :py:meth:`~set_column_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -794,12 +795,12 @@ def col_names(self, names: Optional[List[str]]):
         self.set_column_names(names, in_place=True)
 
     @property
-    def column_names(self) -> Optional[ut.Names]:
+    def column_names(self) -> ut.Names | None:
         """Alias for :py:attr:`~get_column_names`, provided for back-compatibility."""
         return self.get_column_names()
 
     @column_names.setter
-    def column_names(self, names: Optional[List[str]]):
+    def column_names(self, names: list[str] | None):
         """Alias for :py:meth:`~set_column_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -814,7 +815,7 @@ def column_names(self, names: Optional[List[str]]):
     ######>> assay names <<######
     #############################
 
-    def get_assay_names(self) -> List[str]:
+    def get_assay_names(self) -> list[str]:
         """Get assay names.
 
         Returns:
@@ -822,7 +823,7 @@ def get_assay_names(self) -> List[str]:
         """
         return list(self.assays.keys())
 
-    def set_assay_names(self, names: List[str], in_place: bool = False) -> BaseSE:
+    def set_assay_names(self, names: list[str], in_place: bool = False) -> BaseSE:
         """Replace :py:attr:`~summarizedexperiment.BaseSE.BaseSE.assays`'s names.
 
         Args:
@@ -849,12 +850,12 @@ def set_assay_names(self, names: List[str], in_place: bool = False) -> BaseSE:
         return output
 
     @property
-    def assay_names(self) -> List[str]:
+    def assay_names(self) -> list[str]:
         """Alias for :py:attr:`~get_assay_names`."""
         return self.get_assay_names()
 
     @assay_names.setter
-    def assay_names(self, names: List[str]):
+    def assay_names(self, names: list[str]):
         """Alias for :py:attr:`~set_assay_names` with ``in_place = True``.
 
         As this mutates the original object, a warning is raised.
@@ -869,7 +870,7 @@ def assay_names(self, names: List[str]):
     ######>> assay getters <<#######
     ################################
 
-    def get_assay(self, assay: Union[int, str]) -> Any:
+    def get_assay(self, assay: int | str) -> Any:
         """Convenience method to access an :py:attr:`~summarizedexperiment.BaseSE.BaseSE.assays` by name or index.
 
         Args:
@@ -901,11 +902,11 @@ def get_assay(self, assay: Union[int, str]) -> Any:
 
         raise TypeError(f"'assay' must be a string or integer, provided '{type(assay)}'.")
 
-    def assay(self, assay: Union[int, str]) -> Any:
+    def assay(self, assay: int | str) -> Any:
         """Alias for :py:attr:`~assay`. For backwards compatibility"""
         return self.get_assay(assay)
 
-    def set_assay(self, name: Union[str, int], assay: Any, in_place: bool = False) -> BaseSE:
+    def set_assay(self, name: str | int, assay: Any, in_place: bool = False) -> BaseSE:
         """Add or replace :py:attr:`~summarizedexperiment.BaseSE.BaseSE.assays`'s.
 
         Args:
@@ -958,14 +959,14 @@ def set_assay(self, name: Union[str, int], assay: Any, in_place: bool = False) -
     ######>> slicers <<#######
     ##########################
 
-    def _normalize_row_slice(self, rows: Union[str, int, bool, Sequence]):
+    def _normalize_row_slice(self, rows: str | int | bool | Sequence):
         _scalar = None
         if not (isinstance(rows, slice) and rows == slice(None)):
             rows, _scalar = ut.normalize_subscript(rows, len(self._rows), self._row_names)
 
         return rows, _scalar
 
-    def _normalize_column_slice(self, columns: Union[str, int, bool, Sequence]):
+    def _normalize_column_slice(self, columns: str | int | bool | Sequence):
         _scalar = None
         if not (isinstance(columns, slice) and columns == slice(None)):
             columns, _scalar = ut.normalize_subscript(columns, len(self._cols), self._column_names)
@@ -974,9 +975,9 @@ def _normalize_column_slice(self, columns: Union[str, int, bool, Sequence]):
 
     def subset_assays(
         self,
-        rows: Optional[Union[str, int, bool, Sequence]],
-        columns: Optional[Union[str, int, bool, Sequence]],
-    ) -> Dict[str, Any]:
+        rows: str | int | bool | Sequence | None,
+        columns: str | int | bool | Sequence | None,
+    ) -> dict[str, Any]:
         """Subset all assays by the slice defined by rows and columns.
 
         If both ``row_indices`` and ``col_indices`` are None, a shallow copy of the
@@ -1028,8 +1029,8 @@ def subset_assays(
 
     def _generic_slice(
         self,
-        rows: Optional[Union[str, int, bool, Sequence]],
-        columns: Optional[Union[str, int, bool, Sequence]],
+        rows: str | int | bool | Sequence | None,
+        columns: str | int | bool | Sequence | None,
     ) -> SliceResult:
         """Slice ``SummarizedExperiment`` along the rows and/or columns, based on their indices or names.
 
@@ -1085,8 +1086,8 @@ def _generic_slice(
 
     def get_slice(
         self,
-        rows: Optional[Union[str, int, bool, Sequence]],
-        columns: Optional[Union[str, int, bool, Sequence]],
+        rows: str | int | bool | Sequence | None,
+        columns: str | int | bool | Sequence | None,
     ) -> BaseSE:
         """Alias for :py:attr:`~__getitem__`, for back-compatibility."""
 
@@ -1104,7 +1105,7 @@ def get_slice(
 
     def __getitem__(
         self,
-        args: Union[int, str, Sequence, tuple],
+        args: int | str | Sequence | tuple,
     ) -> BaseSE:
         """Subset a ``SummarizedExperiment``.