Check map value doesn't exist

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }
using { /UnrealEngine.com/Temporary/Diagnostics }

game_device := class(creative_device):

    Map: [int]int = map{}

    OnBegin<override>()<suspends>:void=

        if(not Map[0]). Print("No value")