Returns the class registered as the order specification
    visitor utility under the given name (one of the
    :const:`everest.querying.base.EXPRESSION_KINDS` constants).

    :returns: class implementing
        :class:`everest.interfaces.IOrderSpecificationVisitor`

def get_order_specification_visitor(name, registry=None):
    """
    Returns the class registered as the order specification
    visitor utility under the given name (one of the
    :const:`everest.querying.base.EXPRESSION_KINDS` constants).

    :returns: class implementing
        :class:`everest.interfaces.IOrderSpecificationVisitor`
    """
    if registry is None:
        registry = get_current_registry()
    return registry.getUtility(IOrderSpecificationVisitor, name=name)