Boundary Traversal of binary tree

//logic is simple,get root node first then left boundary then leafes then right boundary
//left and right fun not printing root because we are passing it root->left and rppt->right
//left and right fun not printing leaves we are printing data of only that nodes which have either root->left or root->right.

def left_tra(root, ans):
    if root and (root.left or root.right):  # skip leaf nodes
        ans.append(root.data)
        if root.left:
            left_tra(root.left, ans)
        else:
            left_tra(root.right, ans)

def leaves(root, ans):
    if root is None:
        return
    if root.left is None and root.right is None:
        ans.append(root.data)
    leaves(root.left, ans)
    leaves(root.right, ans)

def right_tra(root, ans):
    if root and (root.left or root.right):  # skip leaf nodes
        if root.right:
            right_tra(root.right, ans)
        else:
            right_tra(root.left, ans)
        ans.append(root.data)  # add after recursion (to reverse)

class Solution:
    def boundaryTraversal(self, root):
        if not root:
            return []
        ans = [root.data]

        left_tra(root.left, ans)
        leaves(root.left, ans) #We have asked leaves two times because if tree has only one node,it will work,
        leaves(root.right,ans)
        right_tra(root.right, ans)

        return ans