work on python 3 compatibility
diff --git a/serial/urlhandler/protocol_loop.py b/serial/urlhandler/protocol_loop.py
index a414839..71fdcf7 100644
--- a/serial/urlhandler/protocol_loop.py
+++ b/serial/urlhandler/protocol_loop.py
@@ -104,7 +104,7 @@
                     self.logger.debug('enabled logging')
                 else:
                     raise ValueError('unknown option: %r' % (option,))
-        except ValueError, e:
+        except ValueError as e:
             raise SerialException('expected a string in the form "[loop://][option[/option...]]": %s' % e)
 
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