code: function (chain) {
          if (chain.readable) {
              chain.chainAfter = chain.chainAfter || Pipe.Chain.prototype.chainAfter;
              chain.nextChain = chain.nextChain || Pipe.Chain.prototype.nextChain;
          }
          if (chain.writable) { // Duplex
              chain.chainBefore = chain.chainBefore || Pipe.Chain.prototype.chainBefore;
              chain.previousChain = chain.previousChain || Pipe.Chain.prototype.previousChain;
          }
  
          chain.autoEnhance = true;
  
          chain.enhanceForeignStream = chain.enhanceForeignStream || Pipe.Chain.prototype.enhanceForeignStream;
  
      }
docs: Enhance a stream to a chainable one
  @private
  @param {stream} chain