def bool_attribute(element, attribute, default=True):
    """
    Returns the bool value of an attribute, or a default if it's not defined
    :param element: The XML Element object
    :type  element: etree._Element

    :param attribute: The name of the attribute to evaluate
    :type  attribute: str

    :param default: The default boolean to return if the attribute is not defined
    :type  default: bool

    :rtype: bool
    """
    attribute_value = element.get(attribute)

    if attribute_value:
        return attribute_value == 'true'

    return default