'Return an iterable of model.Sample objects.
:param filter_expr: Filter expression for query.
:param orderby: List of field name and direction pairs for order by.
:param limit: Maximum number of results to return.'

@staticmethod
def query_samples(filter_expr=None, orderby=None, limit=None):

    raise ceilometer.NotImplementedError('Complex    query    for    samples    is    not    implemented.')
