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diff --git a/src/static/js/broadcast_revisions.js b/src/static/js/broadcast_revisions.js
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+++ b/src/static/js/broadcast_revisions.js
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+/**
+ * This code is mostly from the old Etherpad. Please help us to comment this code. 
+ * This helps other people to understand this code better and helps them to improve it.
+ * TL;DR COMMENTS ON THIS FILE ARE HIGHLY APPRECIATED
+ */
+
+/**
+ * Copyright 2009 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// revision info is a skip list whos entries represent a particular revision
+// of the document.  These revisions are connected together by various
+// changesets,  or deltas, between any two revisions.
+
+function loadBroadcastRevisionsJS()
+{
+  function Revision(revNum)
+  {
+    this.rev = revNum;
+    this.changesets = [];
+  }
+
+  Revision.prototype.addChangeset = function(destIndex, changeset, timeDelta)
+  {
+    var changesetWrapper = {
+      deltaRev: destIndex - this.rev,
+      deltaTime: timeDelta,
+      getValue: function()
+      {
+        return changeset;
+      }
+    };
+    this.changesets.push(changesetWrapper);
+    this.changesets.sort(function(a, b)
+    {
+      return (b.deltaRev - a.deltaRev)
+    });
+  }
+
+  revisionInfo = {};
+  revisionInfo.addChangeset = function(fromIndex, toIndex, changeset, backChangeset, timeDelta)
+  {
+    var startRevision = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
+    var endRevision = revisionInfo[toIndex] || revisionInfo.createNew(toIndex);
+    startRevision.addChangeset(toIndex, changeset, timeDelta);
+    endRevision.addChangeset(fromIndex, backChangeset, -1 * timeDelta);
+  }
+
+  revisionInfo.latest = clientVars.totalRevs || -1;
+
+  revisionInfo.createNew = function(index)
+  {
+    revisionInfo[index] = new Revision(index);
+    if (index > revisionInfo.latest)
+    {
+      revisionInfo.latest = index;
+    }
+
+    return revisionInfo[index];
+  }
+
+  // assuming that there is a path from fromIndex to toIndex, and that the links
+  // are laid out in a skip-list format
+  revisionInfo.getPath = function(fromIndex, toIndex)
+  {
+    var changesets = [];
+    var spans = [];
+    var times = [];
+    var elem = revisionInfo[fromIndex] || revisionInfo.createNew(fromIndex);
+    if (elem.changesets.length != 0 && fromIndex != toIndex)
+    {
+      var reverse = !(fromIndex < toIndex)
+      while (((elem.rev < toIndex) && !reverse) || ((elem.rev > toIndex) && reverse))
+      {
+        var couldNotContinue = false;
+        var oldRev = elem.rev;
+
+        for (var i = reverse ? elem.changesets.length - 1 : 0;
+        reverse ? i >= 0 : i < elem.changesets.length;
+        i += reverse ? -1 : 1)
+        {
+          if (((elem.changesets[i].deltaRev < 0) && !reverse) || ((elem.changesets[i].deltaRev > 0) && reverse))
+          {
+            couldNotContinue = true;
+            break;
+          }
+
+          if (((elem.rev + elem.changesets[i].deltaRev <= toIndex) && !reverse) || ((elem.rev + elem.changesets[i].deltaRev >= toIndex) && reverse))
+          {
+            var topush = elem.changesets[i];
+            changesets.push(topush.getValue());
+            spans.push(elem.changesets[i].deltaRev);
+            times.push(topush.deltaTime);
+            elem = revisionInfo[elem.rev + elem.changesets[i].deltaRev];
+            break;
+          }
+        }
+
+        if (couldNotContinue || oldRev == elem.rev) break;
+      }
+    }
+
+    var status = 'partial';
+    if (elem.rev == toIndex) status = 'complete';
+
+    return {
+      'fromRev': fromIndex,
+      'rev': elem.rev,
+      'status': status,
+      'changesets': changesets,
+      'spans': spans,
+      'times': times
+    };
+  }
+}
+
+exports.loadBroadcastRevisionsJS = loadBroadcastRevisionsJS;