Pair implementation in Smalltalk-72 style

pair.js

function pair(left, right) {
    return {
        left() {
            if (arguments.length == 1) left = arguments[0];
            return left;
        },
        right() {
            if (arguments.length == 1) right = arguments[0];
            return right;
        },
        toString() {
            return `(${left}, ${right})` ;
        },
        print() {
            console.log(String(this));
        }
    };
}

let c = pair("john", "lenon");
c.print();
let d = pair("abc", "def");
c.left(d);
c.print();

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.106.9352&rep=rep1&type=pdf

☞ pair ← class | left right
  (
  ¤ isnew  ⇒ ( ☞ left ← ☐.  ☞ right ← ☐. )
  ¤ left ⇒ ( ¤ ← ⇒ (⇑ ☞ left ← ☐)  ⇑ left. )
  ¤ right ⇒ ( ¤ ← ⇒ (⇑ ☞ right ← ☐)  ⇑ right. )
  ¤ print ⇒ ( '(' print. left print. ',' print. right print. ')' print. )
  )!