input: 
  def isSubTree(T: Node, S: Node) -> bool:
      """Check if the binary tree S is a subtree of the binary tree T.
      >>> T1 = Node(26)
      >>> T1.left = Node(10)
      >>> T1.right = Node(3)
      >>> T1.left.left = Node(4)
      >>> T1.left.right = Node(6)
      >>> T1.left.left.right = Node(30)
      >>> T1.right.right = Node(3)
      >>> S1 = Node(10)
      >>> S1.left = Node(4)
      >>> S1.right = Node(6)
      >>> S1.left.right = Node(30)
      >>> isSubTree(T1, S1)
      True
      >>> S2 = Node(4)
      >>> S2.left = Node(3)
      >>> isSubTree(T1, S2)
      False
      """
      if S is None: 
          return True
    
      if T is None: 
          return False
    
      if areIdentical(T, S): 
          return True
    
      return isSubTree(T.left, S) or isSubTree(T.right, S) 
    
    
  def areIdentical(T: Node, S: Node) -> bool: 
        
      if T is None and S is None: 
          return True
    
      if T is None or S is None: 
          return False
    
      return (T.data == S.data and areIdentical(T.left, S.left)and
          areIdentical(T.right, S.right))
  
output:     if S is None: 
          return True
    
      if T is None: 
          return False
    
      if areIdentical(T, S): 
          return True
    
      return isSubTree(T.left, S) or isSubTree(T.right, S) 
    
    
  def areIdentical(T: Node, S: Node) -> bool: 
        
      if T is None and S is None: 
          return True
    
      if T is None or S is None: 
          return False
    
      return (T.data == S.data and areIdentical(T.left, S.left)and
          areIdentical(T.right, S.right))