code: function createWatcher(inPath, callback) {
      if (!inPath) {
          throw new Error('Input path argument is required');
      }
  
      if (!callback) {
          throw new Error('Callback argument is required');
      }
  
      return function watcher() {
          watch(inPath, callback);
      };
  }
docs: Higher order function to create gulp function that watches files and calls a callback on changes.
  @param  {string|string[]} inPath The globs to the files that need to be watched.
  @param  {function} callback Callback to be called when the watched files change.
  @return {function} Function that can be used as a gulp task