code: function(filename, options) {
      var self = this;
      var stream;
      return utils.fs.exists(filename)
        .then(function(exists) {
          if (!exists) {
            throw new Error('File not found: ' + filename);
          }
          stream = fs.createReadStream(filename);
          return self.read(stream, options)
            .catch(function(error) {
              stream.close();
              throw error;
            });
        })
        .then(function(workbook) {
          stream.close();
          return workbook;
        });
    }
docs: =============================================================================== Workbook ========================================================================= Read