code: def test_frame_map_dont_convert_datetime64():
      df = DataFrame({"x1": [datetime(1996, 1, 1)]})
  
      df = df.map(lambda x: x + BDay())
      df = df.map(lambda x: x + BDay())
  
      result = df.x1.dtype
      assert result == "M8[ns]"
  
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 11 for calling a global function with example usage: test_frame_map_dont_convert_datetime64() without return types