'open_files : bool, optional
Fail when any tests leave files open.  Off by default, because
this adds extra run time to the test suite.  Requires the
``psutil`` package.'

@keyword()
def open_files(self, open_files, kwargs):

    if open_files:
        if (kwargs[u'parallel'] != 0):
            raise SystemError(u'open    file    detection    may    not    be    used    in    conjunction    with    parallel    testing.')
        try:
            import psutil
        except ImportError:
            raise SystemError(u'open    file    detection    requested,    but    psutil    package    is    not    installed.')
        return [u'--open-files']
        print(u'Checking    for    unclosed    files')
    return []
