Create function by program and store as variable ?

[xset]

When i do it in CAS programming mode i can't force to execute EXPR and EVAL, they just become symbolic names.

I've found that one can see rewritten body of CAS function translated in something like XCas syntax ??? I suspect these code executed by CAS engine.

Found undocumented shit:
program(x,0,x)
gives function x->x

also works in CAS window expr("program(x,0,x)")
gives functional object which you can store in variable.
I also found undocumented mysterious functions bloc(expr1,expr2) which allow group expressions within functional declaration.