code: function ensure(file, defaults, cb) {
  	fse.pathExists(file, (err, exists) => {
  		if (err) {
  			return cb(err);
  		}
  
  		if (exists) {
  			return cb();
  		}
  
  		fse.outputJson(file, defaults || {}, cb);
  	});
  }
docs: Internal. Check if the file exist and if don't then create the file with the same
  content as default (or {} if default is falsy).
  
  @param {string} file File path .
  @param {object} defaults Default value if it has to create the file.
  @param {function} cb Callback called when the path existance was validated. Takes one
  argument, the error (if any).
  @returns {void} Nothing.