code: function(from, to, lines) {
      var chain = [];
      for (var i = 0; i < lines.length; i++) {
        var end = (i == lines.length - 1) ? to : this.container.ownerDocument.createElement("BR");
        chain.push({from: from, to: end, text: cleanText(lines[i])});
        from = end;
      }
      this.pushChains([chain], from == null && to == null);
      this.notifyEnvironment();
    }
docs: Push a changeset into the document.