1import re 2 3NAME_PATTERN = r"^[_a-zA-Z][_a-zA-Z0-9]*$" 4COMPILED_NAME_PATTERN = re.compile(NAME_PATTERN) 5 6 7def assert_valid_name(name): 8 # type: (str) -> None 9 """Helper to assert that provided names are valid.""" 10 assert COMPILED_NAME_PATTERN.match( 11 name 12 ), 'Names must match /{}/ but "{}" does not.'.format(NAME_PATTERN, name) 13 return None 14