def kill signal = 'TERM', wait = false
      Process.kill signal, self.pid
      val = status if wait
      @stdin.close
      @stdout.close
      @stderr.close
      val
    end
def kill signal = 'TERM', wait = false
      Process.kill signal, self.pid
      val = status if wait
      @stdin.close
      @stdout.close
      @stderr.close
      val
    end
Kills the child process.