Function expression

docs/tests/v2/es6/js/sanddance.js:131348–131356

* Parse an expression given the argument signature and body code.

(args, code, ctx)

 * Parse an expression given the argument signature and body code.
 */
function expression(args, code, ctx) {
  // wrap code in return statement if expression does not terminate
  if (code[code.length - 1] !== ';') {
    code = 'return(' + code + ');';
  }

  var fn = Function.apply(null, args.concat(code));
  return ctx && ctx.functions ? fn.bind(ctx.functions) : fn;
}
/**
 * Parse an expression used to update an operator value.
 */