code: def get_user_orders(self, user_id=None, changed_since=None):
          
          if user_id:
              url = '/users/{0}/orders/'.format(user_id)
          else:
              url = '/users/me/orders/'
  
          data = {}
          if changed_since:
              data['changed_since'] = changed_since
          return self.get(url, data=data)
docs: Returns a paginated response of orders, under the key orders, of all
          orders the user has placed (i.e. where the user was the person buying
          the tickets).
  
          GET users/:id/orders/
  
          :param int user_id: (optional) The id assigned to a user. Leave empty
              to get current user.
          :param datetime changed_since: (optional) Only return attendees changed
              on or after the time given
  
          .. note:: A datetime represented as a string in ISO8601 combined date
              and time format, always in UTC.