code: def _traverse_tree(tree, path):
          
          path_steps = (step for step in path.split('.') if step != '')
          # Special handling for first step, because the first step isn't under 'objects'
          first_step = path_steps.next()
          subtree = tree[first_step]
  
          for step in path_steps:
              subtree = subtree['children'][step]
          return subtree
docs: Traverses the permission tree, returning the permission at given permission path.