def _ParseIssueRequestKeptAttachments(post_data):
  """Extract attachment ids for attachments kept when updating description

  Args:
    post_data: dict w/ values from the user's HTTP POST form data.

  Returns:
    a list of attachment ids for kept attachments
  """
  kept_attachments = post_data.getall('keep-attachment')
  return [int(aid) for aid in kept_attachments]