code: @Override
      public int getMinAxis() {
          int value = x;
          int axis = 0;
          if (y < value) {
              value = y;
              axis = 1;
          }
          if (z < value) {
              value = z;
              axis = 2;
          }
          if (w < value) {
              axis = 3;
          }
          return axis;
      }
docs: Return the axis with the minimal value.
  
  @return {@link int} axis with minimal value