code: function pushEdit (edits, item, added, removed) {
    var last = edits[edits.length - 1]
  
    if (last && last.added === added && last.removed === removed) {
      last.items.unshift(item) // Not push: edits get reversed later
    } else {
      edits.push({
        items: [item],
        added: added,
        removed: removed
      })
    }
  }
docs: pushEdit(edits, item, added, removed) adds the given item to the array
  of edits. Similar edits are grouped together for conciseness.
  
  @param {Array} edits
  @param {*} item
  @param {Boolean} added
  @param {Boolean} removed