<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Given a binary tree, write a program to calculate the sum of all its nodes.
<|im_end|>
<|im_start|>assistant
def calculateSumOfBinaryTree(root):
    if root == None:
        return 0
    else:
        return root.data + calculateSumOfBinaryTree(root.left) + calculateSumOfBinaryTree(root.right)<|im_end|>
