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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 GetFeedItems(client, feed):
 """Returns the Feed Items for a given Feed. Args: client: an AdWordsClient instance. feed: the Feed we are retrieving Feed Items from. Returns: The Feed Items associated with the given Feed. """

  feed_item_service = client.GetService('FeedItemService', 'v201809')

  feed_items = []
  more_pages = True

  selector = {
      'fields': ['FeedItemId', 'AttributeValues'],
      'predicates': [
          {
              'field': 'Status',
              'operator': 'EQUALS',
              'values': ['ENABLED']
          },
          {
              'field': 'FeedId',
              'operator': 'EQUALS',
              'values': [feed['id']]
          }
      ],
      'paging': {
          'startIndex': 0,
          'numberResults': PAGE_SIZE
      }
  }

  while more_pages:
    page = feed_item_service.get(selector)

    if 'entries' in page:
      feed_items.extend(page['entries'])

    selector['paging']['startIndex'] += PAGE_SIZE
    more_pages = selector['paging']['startIndex'] < int(page['totalNumEntries'])

  return feed_items