input-port-open? -- vonuvoli Definition predicate;
input-port-open? (from r7rs);Procedure variants:
((input-port-open |1...|) -> (true))
input-port-open;... -- at least one time;true;((input-port |1...|) -> (false))
input-port;... -- at least one time;false;((port |1...|) -> (false))
((any |1...|) -> (false))
vs:io -- (vonuvoli io);input-port-open;true;input-port;false;port;any;