@@ -420,10 +420,12 @@ strings representing the files in the current directory. Functions which
420420operate on this output would generally not break if you added another file or
421421two to the directory.
422422
423- Tuples are immutable, meaning that once a tuple has been created, you can't
424- replace any of its elements with a new value. Lists are mutable, meaning that
425- you can always change a list's elements. Only immutable elements can be used as
426- dictionary keys, and hence only tuples and not lists can be used as keys.
423+ Tuples are:term: `immutable `, meaning that once a tuple has been created, you can't
424+ replace any of its elements with a new value. Lists are:term: `mutable `, meaning that
425+ you can always change a list's elements. Only:term: `hashable ` objects can
426+ be used as dictionary keys. Most immutable types are hashable, which is why
427+ tuples, but not lists, can be used as keys. Note, however, that a tuple is
428+ only hashable if all of its elements are hashable.
427429
428430
429431How are lists implemented in CPython?