diff --git a/src/plumpy/__init__.py b/src/plumpy/__init__.py
index 8bb5b0d..043e8e6 100644
--- a/src/plumpy/__init__.py
+++ b/src/plumpy/__init__.py
@@ -4,6 +4,9 @@
 
 import logging
 
+# interfaces
+from .controller import ProcessController
+from .coordinator import Coordinator
 from .events import *
 from .exceptions import *
 from .futures import *
@@ -18,10 +21,6 @@
 from .utils import *
 from .workchains import *
 
-# interfaces
-from .controller import ProcessController
-from .coordinator import Coordinator
-
 __all__ = (
     events.__all__
     + exceptions.__all__
diff --git a/src/plumpy/controller.py b/src/plumpy/controller.py
index 5a411fd..eb524be 100644
--- a/src/plumpy/controller.py
+++ b/src/plumpy/controller.py
@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 from collections.abc import Sequence
 from typing import Any, Protocol
 
@@ -53,7 +54,7 @@ def kill_process(self, pid: 'PID_TYPE', msg: MessageType | None = None) -> Proce
         ...
 
     def continue_process(
-        self, pid: 'PID_TYPE', tag: str|None = None, nowait: bool = False, no_reply: bool = False
+        self, pid: 'PID_TYPE', tag: str | None = None, nowait: bool = False, no_reply: bool = False
     ) -> ProcessResult | None:
         """
         Continue the process
diff --git a/src/plumpy/coordinator.py b/src/plumpy/coordinator.py
index c229a6c..efec498 100644
--- a/src/plumpy/coordinator.py
+++ b/src/plumpy/coordinator.py
@@ -1,8 +1,6 @@
 # -*- coding: utf-8 -*-
-import concurrent.futures
 from typing import TYPE_CHECKING, Any, Callable, Hashable, Pattern, Protocol
 
-
 if TYPE_CHECKING:
     # identifiers for subscribers
     ID_TYPE = Hashable
@@ -15,22 +13,8 @@
     BroadcastSubscriber = Callable[['Coordinator', Any, Any, Any, ID_TYPE], Any]
 
 
-class Communicator(Protocol):
-    def add_rpc_subscriber(self, subscriber: 'RpcSubscriber', identifier: 'ID_TYPE | None' = None) -> Any: ...
-
-    def add_broadcast_subscriber(
-        self, subscriber: 'BroadcastSubscriber', subject_filter: str | Pattern[str] | None = None, identifier=None
-    ) -> Any: ...
-
-    def remove_rpc_subscriber(self, identifier): ...
-
-    def remove_broadcast_subscriber(self, identifier): ...
-
-    def broadcast_send(self, body, sender=None, subject=None, correlation_id=None) -> bool: ...
-
-
 class Coordinator(Protocol):
-    def add_rpc_subscriber(self, subscriber: 'RpcSubscriber', identifier=None) -> Any: ...
+    def add_rpc_subscriber(self, subscriber: 'RpcSubscriber', identifier: 'ID_TYPE | None' = None) -> Any: ...
 
     def add_broadcast_subscriber(
         self,
@@ -41,9 +25,9 @@ def add_broadcast_subscriber(
 
     def add_task_subscriber(self, subscriber: 'TaskSubscriber', identifier: 'ID_TYPE | None' = None) -> 'ID_TYPE': ...
 
-    def remove_rpc_subscriber(self, identifier): ...
+    def remove_rpc_subscriber(self, identifier: 'ID_TYPE | None') -> None: ...
 
-    def remove_broadcast_subscriber(self, identifier): ...
+    def remove_broadcast_subscriber(self, identifier: 'ID_TYPE | None') -> None: ...
 
     def remove_task_subscriber(self, identifier: 'ID_TYPE') -> None: ...
 
@@ -52,7 +36,7 @@ def rpc_send(self, recipient_id: Hashable, msg: Any) -> Any: ...
     def broadcast_send(
         self,
         body: Any | None,
-        sender: str | None = None,
+        sender: Hashable | str | None = None,
         subject: str | None = None,
         correlation_id: 'ID_TYPE | None' = None,
     ) -> Any: ...
diff --git a/src/plumpy/exceptions.py b/src/plumpy/exceptions.py
index ed87f35..51898c7 100644
--- a/src/plumpy/exceptions.py
+++ b/src/plumpy/exceptions.py
@@ -3,12 +3,12 @@
 
 __all__ = [
     'ClosedError',
+    'CoordinatorConnectionError',
+    'CoordinatorTimeoutError',
     'InvalidStateError',
     'KilledError',
     'PersistenceError',
     'UnsuccessfulResult',
-    'CoordinatorConnectionError',
-    'CoordinatorTimeoutError',
 ]
 
 
diff --git a/src/plumpy/futures.py b/src/plumpy/futures.py
index 01be395..d3f627f 100644
--- a/src/plumpy/futures.py
+++ b/src/plumpy/futures.py
@@ -18,7 +18,7 @@ class InvalidFutureError(Exception):
 
 
 @contextlib.contextmanager
-def capture_exceptions(future: Future[Any], ignore: tuple[type[BaseException], ...] = ()) -> Generator[None, Any, None]:
+def capture_exceptions(future, ignore: tuple[type[BaseException], ...] = ()) -> Generator[None, Any, None]:  # type: ignore[no-untyped-def]
     """
     Capture any exceptions in the context and set them as the result of the given future
 
diff --git a/src/plumpy/processes.py b/src/plumpy/processes.py
index c08836e..5d2c021 100644
--- a/src/plumpy/processes.py
+++ b/src/plumpy/processes.py
@@ -1017,7 +1017,7 @@ def _schedule_rpc(self, callback: Callable[..., Any], *args: Any, **kwargs: Any)
         :return: a kiwi future that resolves to the outcome of the callback
 
         """
-        kiwi_future = concurrent.futures.Future()
+        kiwi_future = concurrent.futures.Future()  # type: ignore[var-annotated]
 
         async def run_callback() -> None:
             with capture_exceptions(kiwi_future):