code: def test_map_str():
      # GH 2786
      df = DataFrame(np.random.default_rng(2).random((3, 4)))
      df2 = df.copy()
      cols = ["a", "a", "a", "a"]
      df.columns = cols
  
      expected = df2.map(str)
      expected.columns = cols
      result = df.map(str)
      tm.assert_frame_equal(result, expected)
  
imports: from datetime import datetime
  import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Series, Timestamp, date_range
  import pandas._testing
  from pandas.tseries.offsets import BDay
label_desc: Use image node_id 4 for calling a global function with example usage: test_map_str() without return types