public int CompareTo(object obj)
{
ComparablePair <S, T> op = obj as ComparablePair <S, T>;
if (op == null)
{
return(-1);
}
var k = Item1.CompareTo(op.Item1);
if (k != 0)
{
return(k);
}
else
{
return(Item2.CompareTo(op.Item2));
}
}