bpo-30296 Remove unnecessary tuples, lists, sets, and dicts (#1489)

* Replaced list(<generator expression>) with list comprehension
* Replaced dict(<generator expression>) with dict comprehension
* Replaced set(<list literal>) with set literal
* Replaced builtin func(<list comprehension>) with func(<generator
  expression>) when supported (e.g. any(), all(), tuple(), min(), &
  max())

Lib/tokenize.py

@@ -142,7 +142,7 @@ def _all_string_prefixes():
     #  'rf'). The various permutations will be generated.
     _valid_string_prefixes = ['b', 'r', 'u', 'f', 'br', 'fr']
     # if we add binary f-strings, add: ['fb', 'fbr']
-    result = set([''])
+    result = {''}
     for prefix in _valid_string_prefixes:
         for t in _itertools.permutations(prefix):
             # create a list with upper and lower versions of each