Add visit, which should in theory mean all the state of this PMC gets serialized.
Add visit, which should in theory mean all the state of this PMC gets serialized.

cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp