code: function Transform(position, rotation) {
    if (!(this instanceof Transform)) {
      return new Transform(position, rotation);
    }
    this.p = Vec2.zero();
    this.q = Rot.identity();
    if (typeof position !== 'undefined') {
      this.p.set(position);
    }
    if (typeof rotation !== 'undefined') {
      this.q.set(rotation);
    }
  }
docs: TODO merge with Rot 
  A transform contains translation and rotation. It is used to represent the
  position and orientation of rigid frames. Initialize using a position vector
  and a rotation.
  
  @prop {Vec2} position
  @prop {Rot} rotation