[sbml-groups] python snippet to write and read sbml files with groups

Can someone help me to write and read sbml file with groups in python along
with
annotation which is specific to project.
I am attaching file in which I tried to add groups, I am unable to do, I am
sure I am missing some syntax.

sbmlns = SBMLNamespaces(3,1,"groups",1);
sbmlDoc = SBMLDocument(sbmlns)

mplugin = model.getPlugin("groups");
group = mplugin.createGroup();
group.setId("ATPS");
group.setKind("classification");

I get this
<groups:listOfGroups>
      <groups:group groups:id="ATPS" groups:kind="classification">
        <groups:listOfMembers>
          <groups:member groups:idRef="ATPc"/>
          <groups:member groups:idRef="ATPm"/>
        </groups:listOfMembers>
      </groups:group>
    </groups:listOfGroups>

why *groups: listofGroups *I was expecting

*listOfGroups*
I also have xmlns namespace as I need to add annotation specific to project


Thank you