rephrase error message, use union_items

Author: elazarg

mypy/checker.py

@@ -828,7 +828,7 @@ def check_reverse_op_method(self, defn: FuncItem, typ: CallableType,
             elif isinstance(arg_type, UnionType):
                 if not arg_type.has_readable_member(other_method):
                     return
-                arg_types = list(arg_type.iter_deep())
+                arg_types = list(union_items(arg_type))
             else:
                 return
             # We check that each method is fine when dispatched on a proper self argument

mypy/checkmember.py

@@ -373,7 +373,7 @@ def check_method_type(functype: FunctionLike, original_type: Type, is_classmetho
     for item in functype.items():
         if not item.arg_types or item.arg_kinds[0] not in (ARG_POS, ARG_STAR):
             # No positional first (self) argument (*args is okay).
-            msg.fail('Attribute function of type %s does not accept self argument'
+            msg.fail('Attribute function with type %s does not accept self argument'
                      % msg.format(item), context)
         else:
             # Check that self argument has type 'Any' or valid instance/class type.

mypy/types.py

@@ -1130,13 +1130,6 @@ def relevant_items(self) -> List[Type]:
         else:
             return [i for i in self.items if not isinstance(i, NoneTyp)]
 
-    def iter_deep(self) -> Iterator[Type]:
-        for x in self.items:
-            if isinstance(x, UnionType):
-                yield from x.iter_deep()
-            else:
-                yield x
-
     def serialize(self) -> JsonDict:
         return {'.class': 'UnionType',
                 'items': [t.serialize() for t in self.items],