First, a correction! An astute reader pointed out that I made a small mistake in my post on June, 10, with regard to string context keys. My code example showed: type contextKey string const ( KeyUserID = "user_id" KeyTransactionID = "transaction_id" KeyMessageID = "message_id" ) But it should have been: type contextKey string const ( KeyUserID contextKey = "user_id" KeyTransactionID contextKey = "transaction_id" KeyMessageID contextKey = "message_id" ) This is a nasty kind of bug, because th...