What does “hashable” mean in Python?

Question

I tried searching internet but could not find the meaning of hashable.

When they say objects are hashable or hashable objects what does it

Answer 1

Anything that is not mutable (mutable means, likely to change) can be hashed. Besides the hash function to look for, if a class has it, by eg. dir(tuple) and looking for the __hash__ method, here are some examples

#x = hash(set([1,2])) #set unhashable
x = hash(frozenset([1,2])) #hashable
#x = hash(([1,2], [2,3])) #tuple of mutable objects, unhashable
x = hash((1,2,3)) #tuple of immutable objects, hashable
#x = hash()
#x = hash({1,2}) #list of mutable objects, unhashable
#x = hash([1,2,3]) #list of immutable objects, unhashable

List of immutable types:

int, float, decimal, complex, bool, string, tuple, range, frozenset, bytes

List of mutable types:

list, dict, set, bytearray, user-defined classes