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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 GetEntries(self, parser_mediator, top_level=None, **unused_kwargs):
 """Extracts relevant install history entries. Args: parser_mediator (ParserMediator):
 mediates interactions between parsers and other components, such as storage and dfvfs. top_level (dict[str, object]):
 plist top-level key. """

    for entry in top_level:
      datetime_value = entry.get('date', None)
      package_identifiers = entry.get('packageIdentifiers', [])

      if not datetime_value or not package_identifiers:
        continue

      display_name = entry.get('displayName', '<UNKNOWN>')
      display_version = entry.get('displayVersion', '<DISPLAY_VERSION>')
      process_name = entry.get('processName', '<PROCESS_NAME>')
      package_identifiers = ', '.join(package_identifiers)

      event_data = plist_event.PlistTimeEventData()
      event_data.desc = (
          'Installation of [{0:s} {1:s}] using [{2:s}]. Packages: '
          '{3:s}.').format(
              display_name, display_version, process_name, package_identifiers)
      event_data.key = ''
      event_data.root = '/item'

      event = time_events.PythonDatetimeEvent(
          datetime_value, definitions.TIME_DESCRIPTION_WRITTEN)
      parser_mediator.ProduceEventWithEventData(event, event_data)