code: public Quaternionf set(Quaternionfc q) {
          if (q instanceof Quaternionf)
              MemUtil.INSTANCE.copy((Quaternionf) q, this);
          else {
              this.x = q.x();
              this.y = q.y();
              this.z = q.z();
              this.w = q.w();
          }
          return this;
      }
docs: Set this quaternion to be a copy of q.
  
  @param q
  the {@link Quaternionf} to copy
  @return this