Returns true if stream is an open stream; otherwise, returns false.
Streams are open until they have been explicitly closed with close, or until they are implicitly closed due to exit from a with-output-to-string, with-open-file, with-input-from-string, or with-open-stream form.
(open-stream-p *standard-input*) → true
None.
Should signal an error of type type-error if stream is not a stream.
None.
None.
\issue{STREAM-ACCESS:ADD-TYPES-ACCESSORS}