code: function(tagName, parent, fn, other) {
      var buffer = new Ember._RenderBuffer(tagName);
      buffer.parentBuffer = parent;
  
      if (other) { Ember.$.extend(buffer, other); }
      if (fn) { fn.call(this, buffer); }
  
      return buffer;
    }
docs: Create a new child render buffer from a parent buffer. Optionally set
  additional properties on the buffer. Optionally invoke a callback
  with the newly created buffer.
  
  This is a primitive method used by other public methods: `begin`,
  `prepend`, `replaceWith`, `insertAfter`.
  
  @private
  @param {String} tagName Tag name to use for the child buffer's element
  @param {Ember._RenderBuffer} parent The parent render buffer that this
  buffer should be appended to.
  @param {Function} fn A callback to invoke with the newly created buffer.
  @param {Object} other Additional properties to add to the newly created
  buffer.