diff --git a/python/cudf/cudf/core/dataframe.py b/python/cudf/cudf/core/dataframe.py
index bb9cd9b5cc7..3735a949277 100644
--- a/python/cudf/cudf/core/dataframe.py
+++ b/python/cudf/cudf/core/dataframe.py
@@ -6031,11 +6031,12 @@ def nunique(self, axis=0, dropna=True):
         """
         Count number of distinct elements in specified axis.
         Return Series with number of distinct elements. Can ignore NaN values.
-        
+
         Parameters
         ----------
         axis : {0 or 'index', 1 or 'columns'}, default 0
-            The axis to use. 0 or 'index' for row-wise, 1 or 'columns' for column-wise.
+            The axis to use. 0 or 'index' for row-wise, 1 or 'columns' for
+            column-wise.
         dropna : bool, default True
             Don't include NaN in the counts.
 
@@ -6053,12 +6054,11 @@ def nunique(self, axis=0, dropna=True):
         dtype: int64
         """
         if axis != 0:
-            raise NotImplementedError(
-                "axis parameter is not supported yet."
-            )
+            raise NotImplementedError("axis parameter is not supported yet.")
 
         return cudf.Series(super().nunique(method="sort", dropna=dropna))
 
+
 def from_dataframe(df, allow_copy=False):
     return df_protocol.from_dataframe(df, allow_copy=allow_copy)
 
diff --git a/python/cudf/cudf/core/frame.py b/python/cudf/cudf/core/frame.py
index a05986555b1..7e97d655147 100644
--- a/python/cudf/cudf/core/frame.py
+++ b/python/cudf/cudf/core/frame.py
@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import builtins
 import copy
 import pickle
 import warnings
@@ -6420,10 +6421,11 @@ def nunique(self, method: builtins.str = "sort", dropna: bool = True):
             Name and unique value counts of each column in frame.
         """
         return {
-            name: col.distinct_count(method=method, dropna=dropna) 
-                for name, col in self._data.items()
+            name: col.distinct_count(method=method, dropna=dropna)
+            for name, col in self._data.items()
         }
 
+
 def _get_replacement_values_for_columns(
     to_replace: Any, value: Any, columns_dtype_map: Dict[Any, Any]
 ) -> Tuple[Dict[Any, bool], Dict[Any, Any], Dict[Any, Any]]:
diff --git a/python/cudf/cudf/core/single_column_frame.py b/python/cudf/cudf/core/single_column_frame.py
index ea1917acc10..ef479f19363 100644
--- a/python/cudf/cudf/core/single_column_frame.py
+++ b/python/cudf/cudf/core/single_column_frame.py
@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 
+import builtins
 from typing import Any, Dict, MutableMapping, Optional, Tuple, TypeVar, Union
 
 import cupy
@@ -328,7 +329,7 @@ def _make_operands_for_binop(
 
     def nunique(self, method: builtins.str = "sort", dropna: bool = True):
         """
-        Returns count of unique values for the column.
+        Return count of unique values for the column.
 
         Parameters
         ----------
@@ -342,4 +343,4 @@ def nunique(self, method: builtins.str = "sort", dropna: bool = True):
         int
             Number of unique values in the column.
         """
-        return self._column.distinct_count(method=method, dropna=dropna)
\ No newline at end of file
+        return self._column.distinct_count(method=method, dropna=dropna)
diff --git a/python/cudf/cudf/tests/test_dataframe.py b/python/cudf/cudf/tests/test_dataframe.py
index d0a25fd3e8c..ba2caf7c6c8 100644
--- a/python/cudf/cudf/tests/test_dataframe.py
+++ b/python/cudf/cudf/tests/test_dataframe.py
@@ -9095,7 +9095,7 @@ def test_dataframe_nunique(data):
 
 
 @pytest.mark.parametrize(
-    "data", [{ "key": [0, 1, 1, 0, 0, 1], "val": [1, 8, 3, 9, -3, 8]}],
+    "data", [{"key": [0, 1, 1, 0, 0, 1], "val": [1, 8, 3, 9, -3, 8]}],
 )
 def test_dataframe_nunique_index(data):
     gdf = cudf.DataFrame(data)
@@ -9113,4 +9113,3 @@ def test_dataframe_rename_duplicate_column():
         ValueError, match="Duplicate column names are not allowed"
     ):
         gdf.rename(columns={"a": "b"}, inplace=True)
-