Executes a `sketchtool list` command and parse the output
  :cmd: A sketchtool list command :type <list>
  :src_path: File to export. :type <str>
  :returns: A list of pages. Artboards & slices are included in the page hierarchy

def list_cmd(cmd, src_path):
  ''' Executes a `sketchtool list` command and parse the output
  :cmd: A sketchtool list command :type <list>
  :src_path: File to export. :type <str>
  :returns: A list of pages. Artboards & slices are included in the page hierarchy
  '''
  cmd.extend([src_path])

  logger.debug(u'Executing cmd: %s' % cmd)
  result = execute(cmd)
  if not result:
    return None

  logger.debug(u'Raw result: %s' % result)
  list_dict = json.loads(result)
  pages = parse_pages(src_path, list_dict)
  return pages