message: Keep reusing this rad helper function
diff: @@ -213,7 +213,7 @@ function checkInstr(env: Env, instr: bril.Operation, ret: bril.Type | undefined)
  } else if (args.length !== 1) {
  console.error(`cannot return multiple values`);
  } else {
  - checkArgs(env, args, [ret], 'ret');
  + checkTypes(env, instr, {'args': [ret]});
  }
  } else {
  if (args.length !== 0) {
  