test as byte literals

robot.py

@@ -56,10 +56,10 @@ class Robot:
     def serial_read_handler(self, data):
         data = data.strip()
         if data.startswith(b'{') and data.endswith(b'}'):
-            data = data.lstrip('{').rstrip('}')
+            data = data.lstrip(b'{').rstrip(b'}')
         else:
             return      # malformed packet
-        data = data.split(',')
+        data = data.split(b',')
         try:
             self.angle = [int(hex, 16) for hex in data]
         except ValueError: