This is key! Most people try to at least ad hoc'edly treat "inherits from" as "is subtype of". Many typed languages even encode this directly. This is a total

This is key! Most people try to at least ad hoc'edly treat "inherits from" as "is subtype of". Many typed languages even encode this directly. This is a total lie unless LSP is followed, however. LSP doesn't do much more than actually define what the necessary and sufficient properties of the "is subtype of" are.