如何使用Python计算树枝的总和？

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.children = []

def calculate_sum(root):
    if not root:
        return 0
    
    total_sum = root.value
    for child in root.children:
        total_sum += calculate_sum(child)
    
    return total_sum

# 创建树结构
root = TreeNode(1)
child1 = TreeNode(2)
child2 = TreeNode(3)
child3 = TreeNode(4)
child4 = TreeNode(5)

root.children = [child1, child2]
child2.children = [child3, child4]

# 计算树枝的总和
sum_of_branches = calculate_sum(root)
print("树枝的总和为:", sum_of_branches)