code: func DstPort(port uint16) TransportChecker {
  	return func(t *testing.T, h header.Transport) {
  		if p := h.DestinationPort(); p != port {
  			t.Errorf("Bad destination port, got %v, want %v", p, port)
  		}
  	}
  }
docs: // DstPort creates a checker that checks the destination port.