text: export function handle(state, action) {
      const balances = state.balances;
      const canEvolve = state.canEvolve;
      const input = action.input;
      const caller = action.caller;
    
      if (input.function === 'transfer') {
        const target = input.target;
        const qty = input.qty;
    
        if (!Number.isInteger(qty)) {
          throw new ContractError('Invalid value for "qty". Must be an integer');
        }
    
        if (!target) {
          throw new ContractError('No target specified');
        }
    
        if (qty <= 0 || caller === target) {
          throw new ContractError('Invalid token transfer');
        }
    
        if (balances[caller] < qty) {
          throw new ContractError(`Caller balance not high enough to send ${qty} token(s)!`);
        }
    
        // Lower the token balance of the caller
        balances[caller] -= qty;
        if (target in balances) {
          // Wallet already exists in state, add new tokens
          balances[target] += qty;
        } else {
          // Wallet is new, set starting balance
          balances[target] = qty;
        }
    
        return { state };
      }
    
      if (input.function === 'balance') {
        const target = input.target;
        const ticker = state.ticker;
    
        if (typeof target !== 'string') {
          throw new ContractError('Must specify target to get balance for');
        }
    
        if (typeof balances[target] !== 'number') {
          throw new ContractError('Cannot get balance, target does not exist');
        }
    
        return { result: { target, ticker, balance: balances[target] } };
      }
    
      if (input.function === 'evolve' && canEvolve) {
        if (state.owner !== caller) {
          throw new ContractError('Only the owner can evolve a contract.');
        }
    
        state.evolve = input.value;
    
        return { state };
      }
    
      throw new ContractError(`No function supplied or function not recognised: "${input.function}"`);
    }