def _warn_if_env_name_is_not_str(self, name):
if six.PY2 and not isinstance(name, str):<EOL><INDENT>warnings.warn(<EOL>pytest.PytestWarning(<EOL>"<STR_LIT>".format(name)<EOL>)<EOL>)<EOL><DEDENT>
On Python 2, warn if the given environment variable name is not a native str (#4056)