code: def test_str_lower(self):
      self.run_test(
          "def str_lower(s): return s.lower()",
          "ThiS iS a TeST",
          str_lower=[str],
      )
      self.run_test(
          "def str_lower_a(s): return s[0].lower()",
          "ThiS iS a TeST",
          str_lower_a=[str],
      )
  
imports: from pythran.tests import TestEnv
  from pythran.typing import List
  import unittest
label_desc: Use image node_id 18 for calling the TestStr obj's underlying member method code with example usage: obj.test_str_lower() without return types