def create_initial_files(self) -> None:
        """Create the source files we need to run these tests."""
        self.make_file("main_file.py", """\
            import helper1, helper2
            helper1.func1(12)
            helper2.func2(12)
            """)
        self.make_file("helper1.py", """\
            def func1(x):
                if x % 2:
                    print("odd")
            """)
        self.make_file("helper2.py", """\
            def func2(x):
                print("x is %d" % x)
            """)
Create the source files we need to run these tests.
tests/test_html.py