Return the email address to use when creating git objects or exit
    program.

    Parameters
    ----------
    args: parser.parse_args()

    Returns
    -------
    email : `string`
        git user email address

def lookup_email(args):
    """Return the email address to use when creating git objects or exit
    program.

    Parameters
    ----------
    args: parser.parse_args()

    Returns
    -------
    email : `string`
        git user email address
    """
    email = args.email
    if email is None:
        email = gituseremail()

    if email is None:
        raise RuntimeError(textwrap.dedent("""\
            unable to determine a git email
            Specify --email option\
        """))

    debug("email is {email}".format(email=email))

    return email