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