Explain the accounting treatment for a complex lease arrangement involving a sale-leaseback transaction.

A sale-leaseback transaction occurs when an entity (the seller-lessee) sells an asset to another entity (the buyer-lessor) and then leases the asset back from the buyer-lessor. The accounting treatment for a sale-leaseback transaction depends on whether the transaction qualifies as a sale under the applicable accounting standards (ASC 842 in US GAAP or IFRS 16). If the sale-leaseback transaction qualifies as a sale, the seller-lessee derecognizes the asset and recognizes any gain or loss resulting from the sale. The subsequent lease is then accounted for as either a finance lease or an operating lease, depending on whether the lease meets certain criteria. For example, suppose Company A sells a building to Company B for $5 million, which reflects the building's fair value. Company A then leases the building back from Company B. If the transaction qualifies as a sale, Company A would derecognize the building from its balance sheet and recognize a gain or loss for the difference between the selling price ($5 million) and the building's carrying amount. If the carrying amount was $4 million, Company A would recognize a gain of $1 million. The subsequent lease wo....