No it isn't. This is not a unique id. Two different objects could easily have the same hash value. People are mixing up the mathematical term "identity functio

No it isn't. This is not a unique id. Two different objects could easily have the same hash value. People are mixing up the mathematical term "identity function", meaning a function that maps its input directly to its output, with object identity. I have never heard this usage of the phrase, as in a function that takes an object identity as input.