+ my ($class, $start, $end) = @_;
+
+ my $bill_start = $start ? "AND cust_credit_bill._date <= $start" : '';
+ my $bill_end = $end ? "AND cust_credit_bill._date > $end" : '';
+ my $refund_start = $start ? "AND cust_credit_refund._date <= $start" : '';
+ my $refund_end = $end ? "AND cust_credit_refund._date > $end" : '';