In the documentation of numbers.Real:
"In short, those are: a conversion to float, trunc(), round(), math.floor(), math.ceil(), divmod(), //, %, <, <=, >, and >=."
where only "trunc" is not linked if we look at it in html pages.
This is because the function trunc is not in built-in namespace, but in math module. So we should call it math.trunc similarly to math.floor, etc.