def request(self, rpc_command, source=None, filter=None):
        """
        *rpc_command* specifies rpc command to be dispatched either in plain text or in xml element format (depending on command)

        *source* name of the configuration datastore being queried

        *filter* specifies the portion of the configuration to retrieve (by default entire configuration is retrieved)

        :seealso: :ref:`filter_params`

        Examples of usage::

        dispatch('clear-arp-table')

        or dispatch element like ::

        xsd_fetch = new_ele('get-xnm-information')
        sub_ele(xsd_fetch, 'type').text="xml-schema"
        sub_ele(xsd_fetch, 'namespace').text="junos-configuration"
        dispatch(xsd_fetch)
        """

        if ET.iselement(rpc_command):
            node = rpc_command
        else:
            node = new_ele(rpc_command)
        if source is not None:
            node.append(util.datastore_or_url("source", source, self._assert))
        if filter is None:
            node.append(util.build_filter(filter))
        return self._request(node)
dataset/ETHPy150Open osrg/ryu/ryu/contrib/ncclient/operations/retrieve.py/Dispatch.request/operator `is not` -> `is`