How to use the shiv.bootstrap.environment.Environment function in shiv

def test_overrides(self):
        now = str(datetime.now())
        version = "0.0.1"
        env = Environment(now, version)

        assert env.built_at == now
        assert env.shiv_version == version

        assert env.entry_point is None
        with env_var("SHIV_ENTRY_POINT", "test"):
            assert env.entry_point == "test"

        assert env.interpreter is None
        with env_var("SHIV_INTERPRETER", "1"):
            assert env.interpreter is not None

        assert env.root is None
        with env_var("SHIV_ROOT", "tmp"):
            assert env.root == Path("tmp")

def test_roundtrip(self):
        now = str(datetime.now())
        version = "0.0.1"
        env = Environment(now, version)
        env_as_json = env.to_json()
        env_from_json = Environment.from_json(env_as_json)
        assert env.__dict__ == env_from_json.__dict__