code: def test_char(self):
      strings = np.array(["ab", "cd", "ef"], dtype="c").T
      inp, out = self.module.char_test.change_strings(
          strings, strings.shape[1]
      )
      assert inp == pytest.approx(strings)
      expected = strings.copy()
      expected[1, :] = "AAA"
      assert out == pytest.approx(expected)
  
file_path: catboost/contrib/python/numpy/py3/numpy/f2py/tests/test_string.py
imports: import os
  import pytest
  import textwrap
  import numpy
  from .None import util
label_desc: Use image node_id 1 for calling the TestString obj's underlying member method code with example usage: obj.test_char() without return types