def get_attrib_uri(json_dict, attrib):
    """ Get the URI for an attribute.
    """

    url = None
    if type(json_dict[attrib]) == str:
        url = json_dict[attrib]
    elif type(json_dict[attrib]) == dict:
        if json_dict[attrib].get('id', False):
            url = json_dict[attrib]['id']
        elif json_dict[attrib].get('@id', False):
            url = json_dict[attrib]['@id']
    return url