code: def test_diff_float_n(self, datetime_frame):
      rs = datetime_frame.diff(1.0)
      xp = datetime_frame.diff(1)
      tm.assert_frame_equal(rs, xp)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Series, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 14 for calling the TestDataFrameDiff obj's underlying member method code with example usage: obj.test_diff_float_n(datetime_frame) without return types