Fix: Add custom repr to pretty print collections.UserList

[007vedant]

Implemented _userlist_pprint to enable pretty printing of collections.UserList.
Followed convention of previously implemented pprints of other container types of the collections module.
solved against issue #13283

Eg Usage:

In [3]: collections.UserList(range(5))
Out[3]: UserList([0, 1, 2, 3, 4])

In [4]: collections.UserList(range(50))
Out[4]: 
UserList([0,
          1,
          2,
          3,
          4,
         ...
          46,
          47,
          48,
          49])

[yurzo]

Does this meant we recreate the list rather than accessing UserList.data?

[Carreau]

It might be a small optimisation, not sure it is worth it, though the current implementation is identical to _deque_pprint, so we should either reuse _deque_pprint or use obj.data. Up to you.

• a test would indeed be good.

[007vedant]

@Carreau Thanks for the input. I'll start working on it.

[007vedant]

@Carreau I have updated _userlist_pprint with obj.data for optimization and added test for the same in lib/tests/test_pretty.py. All tests have passed. ✔️

Please Review.

[yurzo]

Is this tested anywhere in regression?

[Carreau]

It might be a small optimisation, not sure it is worth it, though the current implementation is identical to _deque_pprint, so we should either reuse _deque_pprint or use obj.data. Up to you.

• a test would indeed be good.

[Carreau]

Do you have an autoformatter setup on your editor by any chance ?

rebased/cleaned and force pushed from 63e98d9 to aca50d2