title: Including an r5rs file into another file in racket
body: <p>One of my courses is using DrRacket for some sections of SICP. We're working on the metacircular evaluator and I have an R5RS code file (<code>set-car!</code> and <code>set-cdr!</code>) which I need to use with my work. Because the R5RS file is roughly 500 lines, I'd prefer to keep it in a separate buffer. How can I include it into my answer buffer's defintions? It appears <code>racket/include</code> requires <code>#lang racket</code>, but <code>set-car!</code> and <code>set-cdr!</code> are not in that language.</p>