python - Something about using inorder traversal prints all the items in the Binary tree -

we don't know how print in traversal order , don't know how print out result if enter binary_str, can us?

class treenode:     def __init__(self , item , left , right):         self.item = item         self.right = right         self.left = left  class binarytree:     def __init__(self):         self.root = none     def add(self , item , binary_str):         binary_str_itr = iter(binary_str)         self.root = self.add_aux(self.root , item , binary_str_itr)      def add_aux(self , current , item , binary_str_itr):         if current none:             current = treenode(none , none , none)         try:             bit = next(binary_str_itr)             if bit == '0':                 current.left = self.add_aux(current.left , item , binary_str_itr)             elif bit == '1':                 current.right = self.add_aux(current.right , item , binary_str_itr)         except stopiteration:             current.item = item         return current       def print_inorder(self):         self.print_inorder_aux(self.root)      def print_inorder_aux(self,current):         if current not none:           #if not base case             self.print_inorder_aux(current.left)             print(current)             self.print_inorder_aux(current.right) 

for inoder traversal, thumb rule

leftchild - root - rightchild  

follow on below link for better understanding