Q about arguments scoping in function definition

In the Maxima language, the f in f(x) is evaluated as follows:
  1) If it is a lambda expression, apply it.
  2) If it is a symbol, then
      a) if it is a built-in function, apply it
      a) if it has a ":=" value, substitute that and go back to (1)
      b) if it has a ":" value or binding, substitute that and go back to (1)
  3) Consider f to be a formal function, and just simplify the expression f(x).

Function references are not resolved at definition time, but at evaluation time.

This is all consistent with "traditional" Lisp semantics (pre-Scheme,
pre-Common Lisp).

If you want to use a functional argument, use apply to avoid this problem, e.g.

     t(n, f, x) := apply(f, [n+x]);

           -s