// We'll only use tST - tST itself will use other tables
\l tST.k

balance: 0; // amount of money inserted
selection: 0; // selection - 0 is no selection
dispensed: 0; // 1 if machine has dispensed successfully
cancelBtn: 0; // 1 if user pressed cancel button

// 1. money inserted
balance+: 3;

// tST -> start selecting, na: next action
na: tST[(balance;selection;dispensed;cancelBtn);0N]; // 0N no args // This will update the state
na[];

// 2. select item
selection: 1;
na: tST[(balance;selection;dispensed;cancelBtn);0N];
na[];

// Here the machine must have dispensed, the stocks SS updated and machine is back to Idle again