'Fetch all migrations applying the filters for a given cell or all
cells.'

def get_migrations(self, ctxt, cell_name, run_locally, filters):

    method_kwargs = dict(filters=filters)
    if cell_name:
        return self._get_migrations_for_cell(ctxt, cell_name, filters)
    message = _BroadcastMessage(self, ctxt, 'get_migrations', method_kwargs, 'down', run_locally=run_locally, need_response=True)
    return message.process()
