code: public Quaternionf add(Quaternionfc q2) {
          x += q2.x();
          y += q2.y();
          z += q2.z();
          w += q2.w();
          return this;
      }
docs: Add <code>q2</code> to this quaternion.
  
  @param q2
  the quaternion to add to this
  @return this