Add docstrings, cleanup

Author: dandavison

temporalio/activity.py

@@ -470,6 +470,7 @@ class _CompleteAsyncError(BaseException):
 def payload_converter() -> temporalio.converter.PayloadConverter:
     """Get the payload converter for the current activity.
 
+    The returned converter has :py:class:`temporalio.converter.ActivitySerializationContext` set.
     This is often used for dynamic activities to convert payloads.
     """
     return _Context.current().payload_converter

temporalio/converter.py

@@ -139,7 +139,6 @@ class ActivitySerializationContext(BaseWorkflowSerializationContext):
     is_local: bool
 
 
-# TODO: duck typing or nominal typing?
 class WithSerializationContext(ABC):
     """Interface for classes that can use serialization context.
 

temporalio/workflow.py

@@ -61,7 +61,6 @@
 import temporalio.workflow
 from temporalio.nexus._util import ServiceHandlerT
 
-from .api.failure.v1.message_pb2 import Failure
 from .types import (
     AnyType,
     CallableAsyncNoParam,
@@ -1148,6 +1147,7 @@ def patched(id: str) -> bool:
 def payload_converter() -> temporalio.converter.PayloadConverter:
     """Get the payload converter for the current workflow.
 
+    The returned converter has :py:class:`temporalio.converter.WorkflowSerializationContext` set.
     This is often used for dynamic workflows/signals/queries to convert
     payloads.
     """