code: function write(filePath, data, mode, callback) {
    async.series([
      cb => mkdir(path.dirname(filePath), cb),
      (cb) => {
        if (mode === WriteMode.UTF8) {
          fs.writeFile(filePath, data, 'utf8', (error) => {
            if (error) {
              console.error(`${filePath}: Could not write the file`);
            }
  
            async.nextTick(cb, error);
          });
        } else if (mode === WriteMode.STREAM) {
          try {
            data.pipe(fs.createWriteStream(filePath));
            async.nextTick(cb, null);
          } catch (error) {
            console.error(`${filePath}: Could not create the write stream`);
            async.nextTick(cb, error);
          }
        }
      },
    ], error => async.nextTick(callback, error));
  }
docs: Write a file.