import base64


def _decode_id(id_):
    """Decode a GitHub user or organization ID returned from GitHub GraphQL API

    Parameters
    ----------
    id_ : str
        An encoded GitHub user or GitHub organization ID returned from
        GitHub GraphQL API, e.g., "MDQ6VXNlcjU4MzIzMQ=="

    Returns
    -------
    str
        The decoded ID, e.g., "04:User583231", "012:Organization75631844"

    """
    return base64.b64decode(id_).decode()