CLN: Remove unnecessary code (#23696)

Author: suminb

pandas/core/accessor.py

@@ -11,7 +11,7 @@
 
 
 class DirNamesMixin(object):
-    _accessors = frozenset([])
+    _accessors = frozenset()
     _deprecations = frozenset(
         ['asobject', 'base', 'data', 'flags', 'itemsize', 'strides'])
 

pandas/core/generic.py

@@ -117,7 +117,7 @@ class NDFrame(PandasObject, SelectionMixin):
                        '_default_fill_value', '_metadata', '__array_struct__',
                        '__array_interface__']
     _internal_names_set = set(_internal_names)
-    _accessors = frozenset([])
+    _accessors = frozenset()
     _deprecations = frozenset(['as_blocks', 'blocks',
                                'convert_objects', 'is_copy'])
     _metadata = []

pandas/core/groupby/groupby.py

@@ -324,7 +324,7 @@ def _group_selection_context(groupby):
 
 class _GroupBy(PandasObject, SelectionMixin):
     _group_selection = None
-    _apply_whitelist = frozenset([])
+    _apply_whitelist = frozenset()
 
     def __init__(self, obj, keys=None, axis=0, level=None,
                  grouper=None, exclusions=None, selection=None, as_index=True,

pandas/tests/dtypes/test_inference.py

@@ -59,7 +59,7 @@ def coerce(request):
     ({'a', 1},                  'set', 'set'),                  # noqa: E241
     (set(),                     'set', 'set-empty'),            # noqa: E241
     (frozenset({'a', 1}),       'set', 'frozenset'),            # noqa: E241
-    (frozenset([]),             'set', 'frozenset-empty'),      # noqa: E241
+    (frozenset(),               'set', 'frozenset-empty'),      # noqa: E241
     (iter([1, 2]),              True,  'iterator'),             # noqa: E241
     (iter([]),                  True,  'iterator-empty'),       # noqa: E241
     ((x for x in [1, 2]),       True,  'generator'),            # noqa: E241