Introduce some stricter typing

jedi/inference/value/klass.py

@@ -38,7 +38,7 @@ py__doc__()                            Returns the docstring for a value.
 """
 from __future__ import annotations
 
-from typing import List, Optional, Tuple
+from typing import List, Optional, Tuple, TYPE_CHECKING, Any
 
 from jedi import debug
 from jedi.parser_utils import get_cached_parent_scope, expr_is_dotted, \
@@ -61,6 +61,9 @@ from inspect import Parameter
 from jedi.inference.names import BaseTreeParamName
 from jedi.inference.signature import AbstractSignature
 
+if TYPE_CHECKING:
+    from jedi.inference import InferenceState
+
 
 class ClassName(TreeNameDefinition):
     def __init__(self, class_value, tree_name, name_context, apply_decorators):
@@ -197,6 +200,15 @@ def get_dataclass_param_names(cls) -> List[DataclassParamName]:
 
 
 class ClassMixin:
+    tree_node: Any
+    parent_context: Any
+    inference_state: InferenceState
+    py__bases__: Any
+    get_metaclasses: Any
+    get_metaclass_filters: Any
+    get_metaclass_signatures: Any
+    list_type_vars: Any
+
     def is_class(self):
         return True