class Github::PageIterator

def prev
  return nil unless prev_page_uri
  page_uri = URI(prev_page_uri)
  params = parse_query(page_uri.query)
  params['page']     = parse_page_number(prev_page_uri)
  params['per_page'] = parse_per_page_number(prev_page_uri)
  response = page_request(page_uri.path, params)
  update_page_links response.links
  response
end