/// TPairHashImpl1
Both \c TPairHashImpl1 and \c TPairHashImpl2 implement the same function: <tt>((a + b) * (a + b + 1) / 2) + a</tt>.
///

/// TPairHashImpl2
Both \c TPairHashImpl1 and \c TPairHashImpl2 implement the same function: <tt>((a + b) * (a + b + 1) / 2) + a</tt>.
///

