How to mock nested / multiple layers of return objects in python

I'm currently struggling to find a good way of mocking multiple layers / nested return values. In other words, I want to return a magic mock that in turn returns a magic mock with it's own set return values. I'm finding this relatively cumbersome and am looking for a more elegant and maintainable solution. I'm trying to test the following code efficiently. the URL returns a json string that needs

[HHR]

mockオブジェクトはmock先が何であれ構造化されない。callする順番にmock_urlopen.return_value.read.return_value.decode.return_valueのようにreturn指定する