// rewrite <id> [=|with|to] <definition>
// - a global version of "replace <id> with"
static SS tok_findRewrites(LS tok) {
  int i;
  SS rewrites = orderedMap();
  while ((i = jfind(tok, "rewrite <id>", (_tok, nIdx) ->
    eqGetOneOf(_tok, nIdx+5, "with", "=", "to"))) >= 0) {
    S token = tok.get(i+2);
    int repStart = i+6;
    int repEnd = smartIndexOf(tok, repStart, "."); // TODO: allow expressions with brackets
    S replacement = joinSubList(tok, repStart, repEnd-1);
    rewrites.put(token, replacement);
  }
  ret rewrites;
}