diff --git a/weave/integrations/anthropic/anthropic_sdk.py b/weave/integrations/anthropic/anthropic_sdk.py
index c991c644eb9..915f3a0a5f0 100644
--- a/weave/integrations/anthropic/anthropic_sdk.py
+++ b/weave/integrations/anthropic/anthropic_sdk.py
@@ -1,10 +1,12 @@
 import importlib
 import typing
 from functools import wraps
+from typing import Any, Union
+
+from typing_extensions import AsyncIterator, Iterator
 
 import weave
-from weave.trace.op_extensions.accumulator import (_IteratorWrapper,
-                                                   add_accumulator)
+from weave.trace.op_extensions.accumulator import _IteratorWrapper, add_accumulator
 from weave.trace.patcher import MultiPatcher, SymbolPatcher
 
 if typing.TYPE_CHECKING:
@@ -16,8 +18,13 @@ def anthropic_accumulator(
     acc: typing.Optional["Message"],
     value: "MessageStreamEvent",
 ) -> "Message":
-    from anthropic.types import (ContentBlockDeltaEvent, Message,
-                                 MessageDeltaEvent, TextBlock, Usage)
+    from anthropic.types import (
+        ContentBlockDeltaEvent,
+        Message,
+        MessageDeltaEvent,
+        TextBlock,
+        Usage,
+    )
 
     if acc is None:
         if hasattr(value, "message"):
@@ -125,9 +132,6 @@ def anthropic_stream_accumulator(
     return acc
 
 
-from typing import Any, Union
-
-from typing_extensions import AsyncIterator, Iterator
 
 
 class AnthropicIteratorWrapper(_IteratorWrapper):
@@ -176,7 +180,7 @@ def wrapper(fn: typing.Callable) -> typing.Callable:
             op,  # type: ignore
             make_accumulator=lambda _: anthropic_stream_accumulator,
             should_accumulate=lambda _: True,
-            iterator_wrapper=AnthropicIteratorWrapper,
+            iterator_wrapper=AnthropicIteratorWrapper,  # type: ignore
         )
 
     return wrapper
diff --git a/weave/integrations/anthropic/anthropic_test.py b/weave/integrations/anthropic/anthropic_test.py
index 453c21804d0..5030930dda2 100644
--- a/weave/integrations/anthropic/anthropic_test.py
+++ b/weave/integrations/anthropic/anthropic_test.py
@@ -2,11 +2,11 @@
 from typing import Any
 
 import pytest
+from anthropic import Anthropic, AsyncAnthropic
+
 import weave
 from weave.trace_server import trace_server_interface as tsi
 
-from anthropic import Anthropic, AsyncAnthropic
-
 model = "claude-3-haiku-20240307"
 # model = "claude-3-opus-20240229"
 
diff --git a/weave/trace/op_extensions/accumulator.py b/weave/trace/op_extensions/accumulator.py
index 3d8f0c232db..7f385449a28 100644
--- a/weave/trace/op_extensions/accumulator.py
+++ b/weave/trace/op_extensions/accumulator.py
@@ -9,6 +9,7 @@
     Generic,
     Iterator,
     Optional,
+    Type,
     TypeVar,
     Union,
 )
@@ -156,7 +157,7 @@ def add_accumulator(
     *,
     should_accumulate: Optional[Callable[[Dict], bool]] = None,
     on_finish_post_processor: Optional[Callable[[Any], Any]] = None,
-    iterator_wrapper: "_IteratorWrapper" = _IteratorWrapper,
+    iterator_wrapper: Type[_IteratorWrapper[Any]] = _IteratorWrapper,
 ) -> Op:
     """This is to be used internally only - specifically designed for integrations with streaming libraries.
 
@@ -182,7 +183,6 @@ def simple_list_accumulator(acc, value):
         acc.append(value)
         return acc
     add_accumulator(fn, simple_list_accumulator) # returns the op with `list(range(9, -1, -1))` as output
-    ```
     """
 
     def on_output(