code: def test_diff_axis1_mixed_dtypes(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": [np.nan, np.nan, np.nan], "B": df["B"] / 2}
      )
  
      result = df.diff(axis=1)
      tm.assert_frame_equal(result, expected)
  
      # GH#21437 mixed-float-dtypes
      df = DataFrame(
          {
              "a": np.arange(3, dtype="float32"),
              "b": np.arange(3, dtype="float64"),
          }
      )
      result = df.diff(axis=1)
      expected = DataFrame({"a": df["a"] * np.nan, "b": df["b"] * 0})
      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 17 for calling the TestDataFrameDiff obj's underlying member method code with example usage: obj.test_diff_axis1_mixed_dtypes() without return types