'Display a list of possibly available reactor names.'

def opt_help_reactors(self):

    rcts = sorted(self._getReactorTypes(), key=attrgetter('shortName'))
    notWorkingReactors = ''
    for r in rcts:
        try:
            namedModule(r.moduleName)
            self.messageOutput.write(('                %-4s DCTB %s\n' % (r.shortName, r.description)))
        except ImportError as e:
            notWorkingReactors += ('                !%-4s DCTB %s    (%s)\n' % (r.shortName, r.description, e.args[0]))
    if notWorkingReactors:
        self.messageOutput.write('\n')
        self.messageOutput.write('                reactors    not    available    on    this    platform:\n\n')
        self.messageOutput.write(notWorkingReactors)
    raise SystemExit(0)
