code: def test_lowercase_unit(list_input):
      lu = units.Lowercase()
      out = lu.transform(list_input)
      assert "is" in out
  
imports: import pytest
  import numpy
  from matchzoo.preprocessors import units
  import matchzoo
  import tempfile
  import os
label_desc: Use image node_id 5 for calling a global function with example usage: test_lowercase_unit(list_input) without return types