How to account for lessors

I have a client who will be leasing equipment to customers. I understand that the asset (stock) is derecognised as the asset under ssap 21 and then reclassified as a debtor (income to be received) but how is the revenue and interest shown in the p/l - is it all at once for the value of the item with the interest shown as income in future periods as it is earned?

any help or basic examples would be great