To add entity meta data to a datastream
        :param datastream: string
        :param options: dict
        :param data: list

def add_entity_meta(self, datastream, options, data):
        """
        To add entity meta data to a datastream
        :param datastream: string
        :param options: dict
        :param data: list
        """
        url = '/datastream/' + str(datastream) + '/entityMeta'
        response = self.http.post(url, data)
        entityMetaList = []
        for entityMeta in response:
            entityMetaList.append(Schemas.EntityMeta(entityMeta=entityMeta))
        return entityMetaList