import base64


def url_base64_decode(s: str) -> bytes:
    """Base64 decode a string using URL semantics.

    Args:
      s (str): The string to decode.

    Returns:
      The base64-decoded bytes.

    References:
      * https://tools.ietf.org/html/rfc4648#section-5
    """
    return base64.b64decode(s + '===', b'-_')