diff --git a/fastapi/applications.py b/fastapi/applications.py
index db0c85169..9e9cf7126 100644
--- a/fastapi/applications.py
+++ b/fastapi/applications.py
@@ -2,7 +2,7 @@ from typing import Any, Callable, Dict, List, Optional, Type
 
 from fastapi import routing
 from fastapi.openapi.docs import get_redoc_html, get_swagger_ui_html
-from fastapi.openapi.models import AdditionalResponse, AdditionalResponseDescription
+from fastapi.openapi.models import AdditionalResponse
 from fastapi.openapi.utils import get_openapi
 from pydantic import BaseModel
 from starlette.applications import Starlette
diff --git a/fastapi/openapi/models.py b/fastapi/openapi/models.py
index 613285930..1be51a1a5 100644
--- a/fastapi/openapi/models.py
+++ b/fastapi/openapi/models.py
@@ -1,6 +1,6 @@
 import logging
 from enum import Enum
-from typing import Any, Callable, ClassVar, Dict, List, Optional, Type, Union
+from typing import Any, Dict, List, Optional, Union
 
 from pydantic import BaseModel, Schema as PSchema
 from pydantic.fields import Field
diff --git a/fastapi/routing.py b/fastapi/routing.py
index 062df5645..187a8faf6 100644
--- a/fastapi/routing.py
+++ b/fastapi/routing.py
@@ -141,11 +141,7 @@ class APIRoute(routing.Route):
         self.response_description = response_description
         self.additional_responses: Dict[int, AdditionalResponseDescription] = {}
         existed_codes = [self.status_code, 422]
-        if isinstance(additional_responses, dict):
-            self.additional_responses = additional_responses.copy()
         for add_response in additional_responses:
-            if isinstance(add_response, int):
-                continue
             assert (
                 add_response.status_code not in existed_codes
             ), f"(Duplicated Status Code): Response with status code [{add_response.status_code}] already defined!"
@@ -156,7 +152,7 @@ class APIRoute(routing.Route):
                 valid_response_models = all(
                     [issubclass(m, BaseModel) for m in response_models]
                 )
-            except TypeError as te:
+            except TypeError:
                 valid_response_models = False
             if not valid_response_models:
                 raise ValueError(