How to use the ihatemoney.models.Bill.query.get function in ihatemoney

def delete_bill(bill_id):
    # fixme: everyone is able to delete a bill
    bill = Bill.query.get(g.project, bill_id)
    if not bill:
        return redirect(url_for(".list_bills"))

    db.session.delete(bill)
    db.session.commit()
    flash(_("The bill has been deleted"))

    return redirect(url_for(".list_bills"))

def put(self, project, bill_id):
        form = get_billform_for(project, True, meta={"csrf": False})
        if form.validate():
            bill = Bill.query.get(project, bill_id)
            form.save(bill, project)
            db.session.commit()
            return bill.id, 200
        return form.errors, 400

def edit_bill(bill_id):
    # FIXME: Test this bill belongs to this project !
    bill = Bill.query.get(g.project, bill_id)
    if not bill:
        raise NotFound()

    form = get_billform_for(g.project, set_default=False)

    if request.method == "POST" and form.validate():
        form.save(bill, g.project)
        db.session.commit()

        flash(_("The bill has been modified"))
        return redirect(url_for(".list_bills"))

    if not form.errors:
        form.fill(bill)

    return render_template("add_bill.html", form=form, edit=True)

def get(self, project, bill_id):
        bill = Bill.query.get(project, bill_id)
        if not bill:
            return "Not Found", 404
        return bill, 200