code: def make_shell_logfiles_url(host, shell_port, _, instance_id=None):
    
    if not shell_port:
      return None
    if not instance_id:
      return "http://%s:%d/browse/log-files" % (host, shell_port)
    else:
      return "http://%s:%d/file/log-files/%s.log.0" % (host, shell_port, instance_id)
docs: Make the url for log-files in heron-shell
    from the info stored in stmgr.
    If no instance_id is provided, the link will
    be to the dir for the whole container.
    If shell port is not present, it returns None.