code: function PassThrough() {
    return {
      buf: '',
  
      write: function(b) {
        this.buf += b;
      },
  
      end: function(b) {
        this.buf += b;
      },
  
      read: function() {
        return this.buf;
      }
    };
  }
docs: Mini-implementation of stream.PassThrough We are far from having need for the full implementation, and we can make assumptions like "many writes, then only one final read" and we can ignore encoding specifics