def METHOD_NAME(self, section: str, option: str) -> Any:
    """Get a single-valued option.
    Performs environment substitution if the value is a string. Other types
    will be converted later as needed.
    """
    name, value = self._get(section, option)
    if isinstance(value, str):
        value = substitute_variables(value, os.environ)
    return name, value