how to use RigidBodyCombiner?[SOLVED]

RigidBodyCombiner return a PandaNode which makes things confusing

RigidBodyCombiner is

its looks like very easy to use:

but this is where problem starts you can reparentTo it so?
I see 2 ways of doing this (and both dont work):

NodePath(RigidBodyCombiner("")) ; reparentTo to that and nodePath.node().collect() - that does not work

use RigidBodyCombiner("") as a PandaNode and use addChild( myNodes… ) - that does not work! have to use myNodes.node() to get the panda node inside and add it. – that doe not work: Assertion failed: !input->get_nodepath().is_empty() at line 937 of panda/src/display/graphicsStateGuardian.cxx

thanks for help!

i was wrong NodePath(RigidBodyCombiner("")) does work! I will write some doc’s on it b/c it gave me x2 time speed improvement (from 20 to 40 fps)
I am very excited!