'Returns a query using GQL query string.
See appengine/ext/gql for more information about GQL.
Args:
query_string: properly formatted GQL query string with the
\'SELECT * FROM <entity>\' part omitted
*args: rest of the positional arguments used to bind numeric references
in the query.
**kwds: dictionary-based arguments (for named parameters).'

@classmethod
def gql(cls, query_string, *args, **kwds):

    return GqlQuery(('SELECT    *    FROM    %s    %s' % (cls.kind(), query_string)), *args, **kwds)
