const r = await mn.api('/blank-bands/' + blankId + '/focus', { method: 'POST', body: {} });
if (r.error && r.error.code === 'DOCUMENT_NOT_ON_SCREEN') {
  // 先把这本文档打开到屏幕上
}

{
  "navigated": true,
  "bridgeApiVersion": "0.91",
  "band": {
    "noteid": "B2C6E32F-323D-458B-994A-20206B73B730",
    "closed": false,
    "owner": "D3085422-2CB9-4B68-A78D-DEE351CF9C38",
    "blankPageNo": 65795,
    "hasInk": false,
    "seq": 1,
    "live": true,
    "inkParts": 0,
    "height": 320,
    "physicalNoteId": "509CC486-1B22-4BD5-8CFF-FC0CC22FF72E",
    "role": "practice",
    "pageNo": 1
  }
}

{
  "error": {
    "code": "CONTENT_CHANGED",
    "message": "目标内容在这期间被改过，请重读后再发。"
  }
}