For Dr. Racket/Scheme Programmers this needs to be done in Dr. Racket in the language eopl (#lang eopl)

Write a procedure number-leaves that take a bintree, and produces a bintree like the original, except the contents of the leaves are numbered starting from 0. For example,

(number-leaves

(interior-node ' foo

(interior-node ' bar

(leaf 26)

(leaf 12))

(interior-node ' baz

(leaf 11)

(interior-node ' quux

(leaf 117)

(leaf 14))

should return

(foo

(bar 0 1)

(baz

2

(quux 3 4)))