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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 GetNotifications(user=None, token=None):
 """Show pending notifications for a user."""

  if not user:
    user = getpass.getuser()
  user_obj = aff4.FACTORY.Open(
      aff4.ROOT_URN.Add("users").Add(user), token=token)
  return list(user_obj.Get(user_obj.Schema.PENDING_NOTIFICATIONS))