docs: function inspect(callback) {
    return function (filename) {
      var chunks = [];
  
      function transform(chunk, encoding, done) {
        /* jshint validthis:true */
        chunks.push(chunk);
        this.push(chunk);
        done();
      }
  
      function flush(done) {
        callback(filename, chunks.join(''), done);
        if (callback.length < 3) {
          done();
        }
      }
  
      return through(transform, flush);
    }
  }