How to use the @nut-tree/nut-js.Key.Add function in @nut-tree/nut-js

static readonly N = NutKey.N;
    static readonly O = NutKey.O;
    static readonly P = NutKey.P;
    static readonly Q = NutKey.Q;
    static readonly R = NutKey.R;
    static readonly S = NutKey.S;
    static readonly T = NutKey.T;
    static readonly U = NutKey.U;
    static readonly V = NutKey.V;
    static readonly W = NutKey.W;
    static readonly X = NutKey.X;
    static readonly Y = NutKey.Y;
    static readonly Z = NutKey.Z;
    static readonly SEPARATOR = NutKey.Period;
    static readonly NUM_LOCK = NutKey.NumLock;
    static readonly ADD = NutKey.Add;
    static readonly MINUS = NutKey.Subtract;
    static readonly MULTIPLY = NutKey.Multiply;
    static readonly DIVIDE = NutKey.Divide;
    static readonly DECIMAL = null;
    static readonly CONTEXT = null;
}