code: def test_diff_axis1_mixed_dtypes_negative_periods(self):
      # GH#32995 operate column-wise when we have mixed dtypes and axis=1
      df = DataFrame(
          {"A": range(3), "B": 2 * np.arange(3, dtype=np.float64)}
      )
  
      expected = DataFrame({"A": -1.0 * df["A"], "B": df["B"] * np.nan})
  
      result = df.diff(axis=1, periods=-1)
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame, Series, Timestamp, date_range
  import pandas._testing
label_desc: Use image node_id 19 for calling the TestDataFrameDiff obj's underlying member method code with example usage: obj.test_diff_axis1_mixed_dtypes_negative_periods() without return types