cpp/utility/hash/operator()

Specializations of std should define an that:


 * Takes a single argument of type.
 * Returns a value of type that represents the hash value of.
 * For two parameters and  that are equal,.
 * For two different parameters and  that are not equal, the probability that  should be very small, approaching.

Return value
a representing the hash value

Exceptions
Hash functions should not throw exceptions.