code: func (b *Bitmap) Clone() *Bitmap {
  	if b == nil {
  		return nil
  	}
  
  	// Create a copy of the bitmap structure.
  	other := &Bitmap{
  		Containers: b.Containers.Clone(),
  	}
  
  	return other
  }
docs: // Clone returns a heap allocated copy of the bitmap.
  // Note: The OpWriter IS NOT copied to the new bitmap.