class Rufus::Scheduler

def do_schedule_at (at, params={}, &block)
  job = params.delete(:job)
  unless job
    jobClass = params[:every] ? EveryJob : AtJob
    b = to_block(params, &block)
    job = jobClass.new(self, at_to_f(at), params[:job_id], params, &b)
  end
  if jobClass == AtJob && job.at < (Time.new.to_f + @precision)
    job.trigger() unless params[:discard_past]
    @non_cron_jobs.delete job.job_id # just to be sure
    return nil
  end
  @non_cron_jobs[job.job_id] = job
  @schedule_queue << job
  job.job_id
end