在树形数据结构中写一个程序，我必须写类名和用户定义的数据类型名为什么是一样的？

class TreeNode:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

    def insert(self, value):
        if value < self.value:
            if self.left is None:
                self.left = TreeNode(value)
            else:
                self.left.insert(value)
        else:
            if self.right is None:
                self.right = TreeNode(value)
            else:
                self.right.insert(value)

    def search(self, value):
        if self.value == value:
            return True
        elif value < self.value and self.left is not None:
            return self.left.search(value)
        elif value > self.value and self.right is not None:
            return self.right.search(value)
        return False

# 使用示例
root = TreeNode(10)
root.insert(5)
root.insert(15)
print(root.search(5))  # 输出: True
print(root.search(20)) # 输出: False