How to use the fs.writeFile function in fs

if (dev) {
    minor = String(parseInt(minor) + 1);
}

// Generate the version file contents.
var contents =
    "# DO NOT EDIT!  NPM AUTOMATICALLY WRITES THIS FILE!\nversion_info = (" +
    major + ", " +
    minor + ", " +
    patch +
    (dev ? ", 'dev'" : "") +
    ")\n__version__ = '.'.join(map(str, version_info))\n";

// Write the contents to the file.
var fs = require("fs");
fs.writeFile("_version.py", contents, function(err) {
    if(err) {
        console.error("Could not write the Python version file", err);
        process.exit(1);
    } else {
        console.log("Python version " + major + "." + minor + "." + patch + (dev ? "dev" : "") + " written");
    }
});

}, function(err, result) {
		if (err) console.error(err)
		else {
			fs.writeFile(outfile,result.css.toString(),'utf8',function(err){
                if (err) console.warn(err.message);
            });
        }
	});
}

.end((err, res) => {
        if (err) callback(err)

        let filepath = url.split('/')[url.split('/').length - 1]

        if (!fs.existsSync(filepath) || (fs.existsSync(filepath) && fs.writeFileSync(filepath) != res.body)) {
          fs.writeFile(filepath, res.body, (err) => {
            callback(null, filepath)
          })
        }
      })
  }

export default function updateSettings(newsettings) {

  //console.log(settingsconf)
  //console.log(newsettings)

  if (!fs.existsSync(prismdir)) {
      fs.mkdirSync(prismdir);
      fs.writeFile(settingsconf, '{"test":"tmp"}');
  }

  //Get current configuration
  //let curconf = JSON.parse(fs.readFileSync(settingsconf));
  //console.log(curconf)


  fs.writeFile(settingsconf, JSON.stringify(newsettings), function(err) {
    if(err) {
        return console.log(err);
    }

    console.log("Prismatica configuration updated!");
  });
}

specCollector(config.glob, function(specs) {
    fs.writeFile(config.specFile, JSON.stringify(specs, null, 4), function (err) {
        if (err) throw err;
        fileCollector(config.specFile, config.comparisonFile, function(files){
            var results = inspector(files);
            var output = spitterOuter(results);
            for (var i = 0; i < output.length; i++) {
                console.log(output[i]);
            }
        });
    });
});

contents.printToPDF({landscape: pageSettings.orientation === 1}, (error, data) => {
          if (error) {
            cb('not_saved')
            return
          }
          fs.writeFile(filepaths[0], data, (error) => {
            if (error) {
              cb('not_saved')
              return
            }
            cb('saved')
          })
        })
      })

return function(callback) {
      fs.writeFile(groupPath, data.embedded.plain, 'utf-8', callback);
    };
  };

templateContextMap[templatePath](project, req, db, function(data) {
            var template = handlebars.compile(contents);
            var newContents = template(data);

            fs.writeFile(filePath, newContents, function(err) {
              if (err) {
                throw err;
              }
            });
          });
        });

saveCss(event, css) {
        _bd_fs.writeFile(`${_bd_config.dataPath}/custom.css`, css, 'utf-8', err => {
            if (err) {
                event.sender.send('save-error', err);
                return;
            }
            event.sender.send('save-ok');
        });
    }
}