Quick and dirty NRZ-L to NRZ-M grc example

Anybody have a suggested solution to do this quickly with existing grc
blocks? I don’t want to write my own if I don’t have to.

I was thinking about this further and I think I may be headed in the
direction. My end objective is to BPSK mod a NRZ-M bit sequence. This
effectively what the existing DBPSK block does (a 1 results in phase
while a 0 does not). Crisis averted.