close closes stream. Closing a stream means that it may no
longer be used in input or output operations. The act of closing
a file stream ends the association between the stream and its
associated file; the transaction with the file system is
terminated, and input/output may no longer be performed on the
stream. If abort is true, an attempt is made to clean up any
side effects of having created stream. If stream performs output
to a file that was created when the stream was created, the file
is deleted and any previously existing file is not superseded.
It is permissible to close an already closed stream, but in that
case the result is implementation-dependent. After stream is
closed, it is still possible to perform the following query
operations upon it: streamp, pathname, truename, merge-
pathnames, pathname-host, pathname-device, pathname-type,
pathname-version, namestring, host-namestring, enough-
namestring, open, probe-file, and directory. The effect of close
on a constructed stream is to close the argume