@public<EOL>def lookup_user(args):
user = args.user<EOL>if user is None:<EOL><INDENT>user = gitusername()<EOL><DEDENT>if user is None:<EOL><INDENT>raise RuntimeError(textwrap.dedent("""<STR_LIT>"""))<EOL><DEDENT>debug("<STR_LIT>".format(user=user))<EOL>return user<EOL>
Return the user name to use when creating git objects or exit
    program.

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

    Returns
    -------
    user: `string`
        git user name