code: public MemorySize truncate(SizeUnit sizeUnit)
    {
      if (getSizeUnit() == sizeUnit)
        return this;
  
      long sizeInBytes = getSizeInBytes();
  
      if (sizeInBytes >= sizeUnit.getBytesCount())
      {
        return new MemorySize(sizeInBytes / sizeUnit.getBytesCount(), sizeUnit);
      }
      else
      {
        return ZERO_SIZES.get(sizeUnit);
      }
    }
docs: Return a new instance of MemorySize that is truncated to the given unit
  
  @param sizeUnit
  @return a new instance of MemorySize that is truncated to the given unit