If i use the async keyword before declaring the return data type here(which i should), i get an “unbound Variable” error

var currentVlaue : Nat = 300;
public query func checkBalance() : async Nat {
    return currentValue;
  };

OR, if i choose to not use the aync keyword, i get the expected “shared query function must have synctatic return type ‘async'”

I did not try anything, as i quite literally do not know what i could do to fix this.