Gets the variables that should be set for this project.
        :return: the variables

def _get_variables(self) -> Dict[str, str]:
        """
        Gets the variables that should be set for this project.
        :return: the variables
        """
        variables = {}  # type: Dict[str, str]
        for group in self.groups:
            setting_variables = self._read_group_variables(group)
            variables.update(setting_variables)
        return variables