- "Takes an object and a location holding a list. If the object is already
- in the list, does nothing. Else, conses the object onto the list. Returns
- NIL. If there is a :TEST keyword, this is used for the comparison."
+ "Takes an object and a location holding a list. If the object is
+ already in the list, does nothing; otherwise, conses the object onto
+ the list. Returns the modified list. If there is a :TEST keyword, this
+ is used for the comparison."