code: func flip(a *Container) *Container { // nolint: deadcode
  	if a.isArray() {
  		return flipArray(a)
  	} else if a.isRun() {
  		return flipRun(a)
  	} else {
  		return flipBitmap(a)
  	}
  }
docs: // flip returns a new container containing the inverse of all
  // bits in a.