diff --git a/ch-13/1-modelling-space/computer/robot_ble_connection.py b/ch-13/1-modelling-space/computer/robot_ble_connection.py
index 88b25b5..a302a15 100644
--- a/ch-13/1-modelling-space/computer/robot_ble_connection.py
+++ b/ch-13/1-modelling-space/computer/robot_ble_connection.py
@@ -1,5 +1,4 @@
 import asyncio
-import typing
 
 import bleak
 
@@ -11,8 +10,8 @@ class BleConnection:
     adafruit_tx_uuid = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
     ble_name = "Adafruit Bluefruit LE"
 
-    def __init__(self, receive_handler: typing.Callable[[bytes], None]):
-        self.ble_client : bleak.BleakClient = None
+    def __init__(self, receive_handler):
+        self.ble_client = None
         self.receive_handler = receive_handler
 
     def _uart_handler(self, _, data: bytes):
diff --git a/ch-13/2-displaying-a-pose/computer/robot_ble_connection.py b/ch-13/2-displaying-a-pose/computer/robot_ble_connection.py
index 88b25b5..a302a15 100644
--- a/ch-13/2-displaying-a-pose/computer/robot_ble_connection.py
+++ b/ch-13/2-displaying-a-pose/computer/robot_ble_connection.py
@@ -1,5 +1,4 @@
 import asyncio
-import typing
 
 import bleak
 
@@ -11,8 +10,8 @@ class BleConnection:
     adafruit_tx_uuid = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
     ble_name = "Adafruit Bluefruit LE"
 
-    def __init__(self, receive_handler: typing.Callable[[bytes], None]):
-        self.ble_client : bleak.BleakClient = None
+    def __init__(self, receive_handler):
+        self.ble_client = None
         self.receive_handler = receive_handler
 
     def _uart_handler(self, _, data: bytes):
diff --git a/ch-13/3-moving-poses-with-sensors/computer/robot_ble_connection.py b/ch-13/3-moving-poses-with-sensors/computer/robot_ble_connection.py
index 88b25b5..a302a15 100644
--- a/ch-13/3-moving-poses-with-sensors/computer/robot_ble_connection.py
+++ b/ch-13/3-moving-poses-with-sensors/computer/robot_ble_connection.py
@@ -1,5 +1,4 @@
 import asyncio
-import typing
 
 import bleak
 
@@ -11,8 +10,8 @@ class BleConnection:
     adafruit_tx_uuid = "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
     ble_name = "Adafruit Bluefruit LE"
 
-    def __init__(self, receive_handler: typing.Callable[[bytes], None]):
-        self.ble_client : bleak.BleakClient = None
+    def __init__(self, receive_handler):
+        self.ble_client = None
         self.receive_handler = receive_handler
 
     def _uart_handler(self, _, data: bytes):