How to set attributes in suds parametrs for request?

Here is a peace of request:

<ContinuousMove xmlns="http://ift.tt/1cvL3Is">
    <ProfileToken>0</ProfileToken>
    <Velocity>
        <PanTilt x="-0.5" y="0" xmlns="http://ift.tt/1cvL1Ag"/>
    </Velocity>
</ContinuousMove>

This request is called like self._client.service.ContinuousMove(0, params), where params is like params = {'PanTilt': [{'x': -0.5}, {'y': 0.5}]}. The main problem is that i cant figure out how to add attributes, not values to the request. On objects it throws error that type is not found, on tuples generates this xml:

<ns0:ContinuousMove>
 <ns0:ProfileToken>0</ns0:ProfileToken>
 <ns0:Velocity>
    <ns1:PanTilt>x</ns1:PanTilt>
    <ns1:PanTilt>0.5</ns1:PanTilt>
    <ns1:PanTilt>y</ns1:PanTilt>
    <ns1:PanTilt>0</ns1:PanTilt>
 </ns0:Velocity>
</ns0:ContinuousMove>