def traverse_depth_first_pre_order(self, callback):
            callback(self)
            for k in self.children:
                self.children[k].traverse_depth_first_pre_order(callback)
Traverses the tree in depth-first top-down order,
dataset/ETHPy150Open mikhaildubov/AST-text-analysis/east/asts/ast.py/AnnotatedSuffixTree.Node.traverse_depth_first_pre_order