Add EventNotSupported exception in errors.py.

bfxapi/websocket/serializers.py

@@ -15,6 +15,8 @@ class _Serializer(object):
     def __call__(self, *values):
         return dict(self.__serialize(*values))
 
+#region Serializers definition for Websocket Public Channels
+
 TradingPairTicker = _Serializer("TradingPairTicker", labels=[
     "BID",
     "BID_SIZE",
@@ -121,4 +123,6 @@ DerivativesStatus = _Serializer("DerivativesStatus", labels=[
     "_PLACEHOLDER",
     "CLAMP_MIN",
     "CLAMP_MAX"
-])
+])
+
+#endregion