code: def create_notebook(self, model=None, path=''):
          
          path = path.strip('/')
          if model is None:
              model = {}
          if 'content' not in model:
              metadata = current.new_metadata(name=u'')
              model['content'] = current.new_notebook(metadata=metadata)
          if 'name' not in model:
              model['name'] = self.increment_filename('Untitled', path)
  
          model['path'] = path
          model['type'] = 'notebook'
          model = self.save_notebook(model, model['name'], model['path'])
  
          return model
docs: Create a new notebook and return its model with no content.