* MapObserver implements Hash
* Rename the hash utility function (in MapObserver) to hash_easy
* Use hash_slice as a helper function to impl Hash trait
* define_python_map_observer macro implements Hash trait
* Also rename hash_easy to hash_simple
* Rename hash_slice to hash_helper
* hash_helper is used to define the implementation of hash function/trait
* Factor out the Hash trait and function for runtime library structs (#1977)
* Simplify hash_simple (of trait MapObserver) (#1977)
* Use hash_one function to make hash_simple a one-liner
* remove hash_helper
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Co-authored-by: Edwin Fernando <ef322@ic.ac.uk>
Co-authored-by: Addison Crump <addison.crump@cispa.de>
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