Passing handlers between bound c++ libs

[Freyr]

I have a python bound physics library that uses handler to process
events. The passing of handlers between c++ and python causes a huge
overhead slowing down the process.  Can I implement a handler in my
custom python bound c++ lib B and pass it to blackbox python bound c++
lib A so that A would call B directly without passing through the
python layer?  Or to phrase the question differently:  Can I pass a
handler from B through python to A so that A will invoke B with out
calling into python code?