port-open -- r7rs Type port;input-port-eof;binary-input-port-open;binary-input-port-eof;binary-output-port-open;textual-input-port-open;textual-input-port-eof;textual-output-port-open;(lambda (value) (and (port? value) (or (input-port-open? value) (output-port-open? value))))