def valid(self) -> bool:
        """
        Check that the path points to a dir that really is a virtualenv with reasonable
        certainty
        """
        if not self.path:
            return False
        bin_dir = self.bin_dir()
        if self._is_windows:
            return (
                bin_dir.joinpath("activate").is_file()
                and bin_dir.joinpath("python.exe").is_file()
                and self.path.joinpath("Lib", "site-packages").is_dir()
            )
        return (
            bin_dir.joinpath("activate").is_file()
            and bin_dir.joinpath("python").is_file()
            and bool(
                next(
                    self.path.glob(
                        os.path.sep.join(("lib", "python3*", "site-packages"))
                    ),
                    False,
                )
            )
        )

        Check that the path points to a dir that really is a virtualenv with reasonable
        certainty
        
poethepoet/virtualenv.py