Python 3.x RECURSION Binary Tree ADT

This is the code that I have so far but I'm unsure as where to go next or if it's even right:

import treenode as tn 

def alter_subtrees(tnode, left_tree_offset, right_tree_offset, root_offset=0):  if tnode is None: return if tn.get_left(tnode): tn.set_data(tn.get_left(tnode), tn.get_data(tn.get_left(tnode) + left_tree_offset) alter_subtrees(tn.get_left(tnode), left_tree_offset, right_tree_offset, root_offset) if tn.get_right(tnode): tn.set_data(tn.get_right(tnode), tn.get_data(tn.get_right(tnode) + right_tree_offset) alter_subtrees(tn.get_right(tnode), left_tree_offset, right_tree_offset, root_offset) 

This is the Code that I imported:

Treenode:

# Defines the tree node ADT # # A treenode is a simple container with three pieces of information # data: the contained information # left: a reference to another treenode or None # right: a reference to another treenode or None # Implementation notes: # This implementation uses a Python dictionary as a record. def create(data, left=None, right=None): """  Create a new treenode for the given data.  Pre-conditions:  data: Any data value to be stored in the treenode  left: Another treenode (or None, by default)  Post-condition:  none  Return:  the treenode created  """  return {'data':data, 'left':left, 'right':right} def get_data(treenode): """  Retrieve the contents of the data field.  Pre-conditions:  node: a node created by create()  Post-conditions:  none  Return  the data value stored previously in the node  """  return treenode['data'] def get_left(tnode): """  Retrieve the contents of the left field.  Pre-conditions:  tnode: a treenode created by create()  Post-conditions:  none  Return  the value stored in left field  """  return tnode['left'] def get_right(tnode): """  Retrieve the contents of the right field.  Pre-conditions:  tnode: a treenode created by create()  Post-conditions:  none  Return  the value stored in right field  """  return tnode['right'] def set_data(tnode, val): """  Set the contents of the data field to val.  Pre-conditions:  tnode: a node created by create()  val: a data value to be stored  Post-conditions:  stores the new data value, replacing the existing value  Return  none  """  tnode['data'] = val def set_left(tnode, val): """  Set the contents of left field to val.  Pre-conditions:  tnode: a treenode created by create()  val: a treenode, or the value None  Post-conditions:  stores the val in left field, replacing the existing value  Return  none  """  tnode['left'] = val def set_right(tnode, val): """  Set the contents of right field to val.  Pre-conditions:  tnode: a treenode created by create()  val: a treenode, or the value None  Post-conditions:  stores the val in right field, replacing the existing value  Return  none  """  tnode['right'] = val 

Example Tree:

atree = tn.create(2) a = tn.create(7) b = tn.create(5) tn.set_left(atree, a) tn.set_right(atree, b) c = tn.create(11) d = tn.create(6) tn.set_left(a, c) tn.set_right(a, d)