如何将嵌套数组的值全部更改为相同的字符串？

def change_nested_array(arr, target):
    if isinstance(arr, list):
        for i in range(len(arr)):
            arr[i] = change_nested_array(arr[i], target)
    else:
        arr = target
    return arr

nested_array = [1, [2, [3, [4, 5], 6], 7], 8]
target_string = "hello"
result = change_nested_array(nested_array, target_string)
print(result)

['hello', ['hello', ['hello', ['hello', 'hello'], 'hello'], 'hello'], 'hello']