John Rumm wrote:
Some notebooks deliberately have one or more USB sockets with yellow
coloured inserts that are powered when the laptop is off, for just this
purpose. Alas they seem to be more the exception than the rule.

If only hotels would have one or more mains sockets with coloured
inserts that are powered when the key card is removed from the slot by
the door.

--
Mike Barnes
Cheshire, England