더욱 깔끔한 비동기 JavaScript 코드를 위해 Promise를 중첩 해제하려면 어떻게 해야 합니까?

exports.viewFile = function(req, res) {
    var fileId = req.params.id;
    boxContentRequest('files/' + fileId + '/content', req.user.box.accessToken)
      .then(function(response) {
          return boxViewerRequest('documents', {url: response.request.href}, 'POST');
      })
      .then(function(response) {
          return boxViewerRequest('sessions', {document_id: response.body.id}, 'POST');
      })
      .then(function(response) {
          console.log(response);
      });
};

somePromise.then(function(r1) {
    return nextPromise.then(function(r2) {
        return anyValue;
    });
}) // resolves with anyValue

     ||
    \||/
     \/

somePromise.then(function(r1) {
    return nextPromise;
}).then(function(r2) {
    return anyValue;
}) // resolves with anyValue as well