Objects always have a default hash value which is sufficient for most cases.
More optimized hashes could be build when various conditions are met.
Used by hash collections to compute hash value and equality between objects.
author  Johann Sorel

Default hasher, used objects hash and equals method.

Hasher which test equality with an identity test.

Calculate hash of given object.
param  candidate
return  hash value

Test if the two given objects are equals.
Any two objects that are equal must have the same hash value.
param  a
param  b
return  true if objects are equal.