code: def test_pad_fillchar(any_string_dtype):
      s = Series(
          ["a", "b", np.nan, "c", np.nan, "eeeeee"],
          dtype=any_string_dtype,
      )
  
      result = s.str.pad(5, side="left", fillchar="X")
      expected = Series(
          ["XXXXa", "XXXXb", np.nan, "XXXXc", np.nan, "eeeeee"],
          dtype=any_string_dtype,
      )
      tm.assert_series_equal(result, expected)
  
      result = s.str.pad(5, side="right", fillchar="X")
      expected = Series(
          ["aXXXX", "bXXXX", np.nan, "cXXXX", np.nan, "eeeeee"],
          dtype=any_string_dtype,
      )
      tm.assert_series_equal(result, expected)
  
      result = s.str.pad(5, side="both", fillchar="X")
      expected = Series(
          ["XXaXX", "XXbXX", np.nan, "XXcXX", np.nan, "eeeeee"],
          dtype=any_string_dtype,
      )
      tm.assert_series_equal(result, expected)
  
imports: from datetime import datetime
  import operator
  import numpy
  import pytest
  from pandas import Series, _testing
label_desc: Use image node_id 13 for calling a global function with example usage: test_pad_fillchar(any_string_dtype) without return types