code: public SparseBitmap xor(SparseBitmap o) {
  		SparseBitmap a = new SparseBitmap();
  		xor2by2(a, this, o);
  		return a;
  	}
docs: Computes the bit-wise logical exclusive or with another bitmap.
  
  @param o
  another bitmap
  @return the result of the bti-wise logical exclusive or