def create_prefix(nick, user, host):
    """ Builds a prefix based on the nick, user, and host provided. This is essentially the
    opposite to parse_prefix().
    
        >>> create_prefix("Jack", "~jack", "000-000-000-000.example.com")
        'Jack!~jack@000-000-000-000.example.com'
    """
    return '{0}!{1}@{2}'.format(nick, user, host)
