code: def in_tree(self, name):
          r
          if self._validate_node_name(name):
              raise RuntimeError("Argument `name` is not valid")
          return name in self._db
docs: r"""
          Test if a node is in the tree.
  
          :param name: Node name to search for
          :type  name: :ref:`NodeName`
  
          :rtype: boolean
  
          :raises: RuntimeError (Argument \`name\` is not valid)