var Batcher = require('byte-stream')
var manualMergeStream = require('manual-merge-stream')
var diff2daff = require('diff2daff')

module.exports = function (diffStream, opts, merge) {
  if (!opts) {
    opts = {}
  }
  var limit = (opts.limit || 20) * 2
  var batchStream = Batcher(limit)
  var vizFn = opts.vizFn || diff2daff

  var mergeStream
  if (merge) mergeStream = manualMergeStream(vizFn, merge)
  else mergeStream = manualMergeStream(vizFn)

  return diffStream.pipe(batchStream).pipe(mergeStream)
}
@@ -292,15 +292,28 @@
 var 
+opts = %7B%0A    
 vizFn
+:
  
-=
  opt
@@ -336,132 +336,30 @@
 daff
-%0A%0A  var mergeStream%0A  if (merge) mergeStream = manualMergeStream(vizFn, merge)%0A  else mergeStream = manualMergeStream(vizFn)
+,%0A    merge: merge%0A  %7D
 %0A%0A  
@@ -400,16 +400,22 @@
 ).pipe(m
+anualM
 ergeStre
@@ -416,11 +416,17 @@
 geStream
+(opts)
 )%0A%7D

Use new manual-merge-stream vizFn opts