code: def __event_exist(self, event_type):
          
          for i in range(self.len()):
              if self.events_list[i][1] < 0 and self.events_list[i][3] == event_type:
                  return i
          return -1
docs: Return the event position, if it exists.
  
          An event exist if:
          * end is < 0
          * event_type is matching
          Return -1 if the item is not found.