Apply suggestions from code review

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>

mypy/sametypes.py

@@ -145,8 +145,8 @@ def visit_union_type(self, left: UnionType) -> bool:
         if isinstance(self.right, UnionType):
             # fast path for simple literals
             def _extract_literals(u: UnionType) -> Tuple[Set[LiteralType], List[Type]]:
-                lit = set()  # type: Set[LiteralType]
-                rem = []  # type: List[Type]
+                lit: Set[LiteralType] = set()
+                rem: List[Type] = []
                 for i in u.items:
                     if is_simple_literal(i):
                         assert isinstance(i, LiteralType)  # type: ignore[misc]

mypy/subtypes.py

@@ -499,7 +499,7 @@ def visit_overloaded(self, left: Overloaded) -> bool:
 
     def visit_union_type(self, left: UnionType) -> bool:
         if isinstance(self.right, Instance):
-            literal_types = set()  # type: Set[Instance]
+            literal_types: Set[Instance] = set()
             # avoid redundant check for union of literals
             for item in left.items:
                 if mypy.typeops.is_simple_literal(item):
@@ -1151,7 +1151,7 @@ def report(*args: Any) -> None:
 
 
 def try_restrict_literal_union(t: UnionType, s: Type) -> Optional[List[Type]]:
-    new_items = []  # type: List[Type]
+    new_items: List[Type] = []
     for i in t.relevant_items():
         it = get_proper_type(i)
         if not mypy.typeops.is_simple_literal(it):