code: function checkInbox(uri, cert) {
    console.log('checking inbox for:', uri, cert)
    shell.ls([null, null, uri, cert], function(err, ret) {
      if (err) {
        console.error(err)
      } else {
        console.log(ret)
      }
  
    })
  }
docs: check a given inbox
  @param  {string} uri  The inbox to check.
  @param  {string} cert Certificate location.