How to calculate a symbol from its immediate node

Say we already have define

a = mx.sym.Variable('a')
b = mx.sym.Variable('b')
c = a+b # name is _plus0_output
d = c/2

and we could calculate c with




to get both c and d.

but how could I calculate d only via c?
sometimes I’d like to use synthetic c to check if the model is robust and in this case I could not get a and b.
I’d like to have something like


Is it possible?