Assertion: racket's string | /r/CapableOf | end with a file extension
Facets:
value: optionally
type: MANNER
Source sentences:
text: A (planet string) form is like a (planet id) form with the identifier converted to a string, except that the string can optionally end with a file extension (i.e., a .) for a ‹path›. A ".ss" file extension is converted to ".rkt".