def connect(self): 
        try:
            self.connection = pymongo.Connection(self.host, self.port)
            self.db = self.connection[self.name]
        except AutoReconnect:
            raise DatabaseException("It's not possible connect to the database")
def sls(n, d):
            gg = te.reduce_axis((0, lengths[n]))
            indices_idx = length_offsets[n] + gg
            data_idx = indices[indices_idx]
            data_val = data[data_idx, d]
            return te.sum(data_val, axis=gg)