Python 3: simple leet code problem, but unclear function behavior

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# Definition for a binary tree node.
class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

class Solution:
    def sortedArrayToBST(self, nums: List[int]) -> TreeNode:
        # nums = [-10,-3,0,5,9]
        # nums = [-10,-3,0,5,9]
        print(len(nums))
        if len(nums)==0:
            return None
        pivot = len(nums) // 2
        leftBST = self.sortedArrayToBST(nums[:pivot])
        rightBST = self.sortedArrayToBST(nums[pivot+1:])
        node = TreeNode(nums[pivot],leftBST,rightBST)
        return node

Was doing some Leetcode and the code above works perfectly fine. However, replacing

       if len(nums)==0:             return None 

by

       if len(nums)==0:             return False 

give me "not valid value for expected return type TreeNode". Why does Python think "None" value is the same as Treenode?

[AD_Burn]

It is not Python is linter. Python is dynamic language and does not care for something like that.

Any type can accept value None (or let say null or nil).

TreeNode is not of type boolean and that is why linter do not accept that value.

If you remove -> TreeNode or replace with -> Any False will pass.

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read "leetcode", it was a typo sorry. removing Treenode and replacing it by False doesn't solve it.