Expand is_named_instance

Author: A5rocks

mypy/types.py

@@ -4040,8 +4040,8 @@ def visit_type_alias_type(self, t: TypeAliasType, /) -> list[mypy.nodes.TypeAlia
         return res
 
 
-def is_named_instance(t: Type, fullnames: str | tuple[str, ...]) -> TypeGuard[Instance]:
-    if not isinstance(fullnames, tuple):
+def is_named_instance(t: Type, fullnames: str | Sequence[str, ...]) -> TypeGuard[Instance]:
+    if isinstance(fullnames, str):
         fullnames = (fullnames,)
 
     t = get_proper_type(t)