List all variable defined in bc command

Question

Is it possible to list all variables (print symbol table) in bc command?

For example

$ bc -q
x=3
y=4
z=x+y
/* a command for listing all variables defined */
/* and it will show:
  x 3
  y 4
  z 7
  or maybe in other format */

If saying "all defined variable" is ambiguous, "all non-zero variables" should also be acceptable.

Answer 1

No, no such command exists in bc.