Hashability makes an object usable as a dictionary key and a set member,
because these data structures use the hash value internally.
- All of Python's immutable built-in objects are hashable, while no mutable
- containers (such as lists or dictionaries) are. Objects which are
- instances of user-defined classes are hashable by default; they all
+ All of Python's immutable built-in objects are hashable; mutable
+ containers (such as lists or dictionaries) are not. Objects which are
+ instances of user-defined classes are hashable by default. They all
compare unequal (except with themselves), and their hash value is derived
from their :func:`id`.