Type() not detecting my class (Tree) in Python 3 -

came across cannot understand properly. please have @ piece of code below. part of program converting binary tree list , record file. problem have fails detect tree object , skips else: part of if statement. put print type(t) in loop before going if statement check if tree object end shows:

 <class '__main__.tree'>  

but python still skips if clause (i tried type(t) tree , type(t) == tree, same result). there must not understand if can see please let me know.

variables @ first step after program skips damn if clause , goes else no reason can grasp :) :

copy = {list} <class 'list'>: [<__main__.tree object @ 0x0000001eaae549b0>]  t = {tree} can bark  cargo = {str} 'can bark'     while len(bot_level) > 0:          copy = bot_level[:]         t in copy:             print(type(t))             if isinstance(t, tree):                 cargo_list.append(t.cargo)                 bot_level.append(t.left)                 bot_level.append(t.right)                 del bot_level[0]             else:                 cargo_list.append(none)                 del bot_level[0]