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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def GetEventTypeString(self, event_type):
 """Retrieves a string representation of the event type. Args: event_type (int):
 event type. Returns: str: description of the event type. """

    if 0 <= event_type < len(self._EVENT_TYPES):
      return self._EVENT_TYPES[event_type]
    return 'Unknown {0:d}'.format(event_type)