create_node (JSONTreeView)

         # File lib/json/editor.rb, line 817
    817:       def create_node(parent, type, content)
    818:         iter = if parent
    819:           model.append(parent)
    820:         else
    821:           new_model = Editor.data2model(nil)
    822:           toplevel.view_new_model(new_model)
    823:           new_model.iter_first
    824:         end
    825:         iter.type, iter.content = type, content
    826:         expand_collapse(parent) if parent
    827:         iter
    828:       end