def get_private_member(element, key):
    """
    This filter returns a private member of an element

    :param element: The requested object
    :type element: object

    :param key: The key of the private variable (without the leading underscore)
    :type key: str

    :return: The value of the private variable
    :rtype: object
    """
    return element[f"_{key}"]