stubs.py

from mitmproxy import http

def request(flow: http.HTTPFlow) -> None:
    if flow.request.pretty_url.startswith("https://www.example.net/exercise"):
        flow.response = http.HTTPResponse.make(
                200,
                b"exercise-content",
                )
    elif flow.request.pretty_url.startswith("https://cdnjs.cloudflare.com/ajax/libs/mathjax"):
        flow.response = http.HTTPResponse.make(
                200,
                b"""
                    window.MathJax = {
                    Hub: {
                        Queue: function() {
                        return function() { };
                        }
                    }
                    }
                """
                )
    elif flow.request.pretty_host != "127.0.0.1":
        flow.response = http.HTTPResponse.make(200, b"")