code: func (bitmap *bitmap) Xor(other *bitmap) *bitmap {
  	if bitmap.Size != other.Size {
  		panic("size not the same")
  	}
  
  	distance := newBitmap(bitmap.Size)
  	xor(distance.data, bitmap.data, other.data)
  
  	return distance
  }
docs: // Xor returns the xor value of two bitmap.