                  return employee
          return None
  
      def notify_call_escalated(self, call):
 
</s> remove     def notify_call_escalated(self, call):  # ...
    def notify_call_completed(self, call):  # ...
    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):  # ... </s> add  </s> remove     def shuffle(self):  # ... </s> add  </s> remove     def park_vehicle(self, vehicle):  # ...
    def remove_vehicle(self):  # ... </s> add  </s> remove         # ...
 </s> add         pass </s> remove     def move_to_front(self, node):  # ...
    def append_to_front(self, node):  # ...
    def remove_from_tail(self):  # ...
 </s> add     def move_to_front(self, node):
        pass

    def append_to_front(self, node):
        pass

    def remove_from_tail(self):
        pass
    def notify_call_escalated(self, call):
        pass

    def notify_call_completed(self, call):
        pass

    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):
        pass
                  return employee
          return None
  
      def notify_call_escalated(self, call):
    def notify_call_escalated(self, call):
        pass

    def notify_call_completed(self, call):
        pass

    def dispatch_queued_call_to_newly_freed_employee(self, call, employee):
        pass
keep keep keep add
 Convert all .py files to be valid Python (#98) 
solutions/object_oriented_design/call_center/call_center.py