def replace_variables(self, text):
        """Replace variable placeholders in `text` with values from the virtual env.

        The variables are:
          - {python-executable}

        Args:
            text: The text to do replacment int.

        Returns: The text after replacement.
        """
        variables = {
            'python-executable': str(self._venv_path / 'bin' / 'python')
        }
        return text.format(**variables)