code: function subtract(point, rhs) {
      if (typeof rhs === 'number') {
          return {
              x: point.x - rhs,
              y: point.y - rhs,
          };
      } else {
          return {
              x: point.x - rhs.x,
              y: point.y - rhs.y,
          };
      }
  }
docs: subtract point or number from point
  @param {Point2D} point
  @param {(Point2D | number)} rhs