code: def test_diff_np(self):
      # TODO(__array_function__): could make np.diff return a Series
      #  matching ser.diff()
  
      ser = Series(np.arange(5))
  
      res = np.diff(ser)
      expected = np.array([1, 1, 1, 1])
      tm.assert_numpy_array_equal(res, expected)
  
file_path: pandas/pandas/tests/series/methods/test_diff.py
imports: import numpy
  import pytest
  from pandas import Series, TimedeltaIndex, date_range
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestSeriesDiff obj's underlying member method code with example usage: obj.test_diff_np() without return types