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

In python it means that the object can be members of sets in order to return a index. That is, they have unique identity/ id.

for example, in python 3.3:

the data structure Lists are not hashable but the data structure Tuples are hashable.