public boolean equals(Object other) {
    	if (other instanceof Pair) {
    		Pair otherPair = (Pair) other;
    		return 
    		((  this.first == otherPair.first ||
    			( this.first != null && otherPair.first != null &&
    			  this.first.equals(otherPair.first))) &&
    		 (	this.second == otherPair.second ||
    			( this.second != null && otherPair.second != null &&
    			  this.second.equals(otherPair.second))) );
    	}

    	return false;
    }