code: function writeToFile(fileContent, filePath) {
    return new Promise((resolve, reject) => {
      fs.writeFile(filePath, fileContent, 'utf8', (err) => {
        if (err) {
          reject(err);
          return;
        }
        resolve(filePath);
      });
    });
  }
docs: Write a string to a file
  @param {string} fileContent the payload of the file
  @param {string} filePath path and filename: where store the file
  @returns {Promise<string>} resolve with the filePath received in input