class Bucket {
   private float capacity;
   private float contents;

   public void pourIn(float addedVolume) {
      float volumePresent = contents + addedVolume;
      contents = constrainedToCapacity(volumePresent);
   }

   private float constrainedToCapacity(float volumePlacedIn) {
      if (volumePlacedIn > capacity) return capacity;
      return volumePlacedIn;
   }
}
