gistfile1.txt

global account david = u'GmRx7DgzV77iBtZRasJzrVJ145RzzuJNNsMxhXP5hTz3';
global account charlie = u'AtTXkZGm96mk2aEU3jY6bfEdEKgBi12yNHg5H2jxXwcN';

global assetDisc usd = a'9H8SP3mHbbcXryCfCfxSxm8UsSRj7wdW1E14FXDsbWV9';
global assetDisc violin = a'EWWr6D2JtM2c5f9DYCrYR4un4DXBw98WUXz5Rektq999';

global int usdAmount;
global int violinAmount;

transition initial -> proposed;
transition initial -> terminal;
transition proposed -> initial;

@initial {charlie}
propose(int usdProposal, int violinProposal) {
  usdAmount = usdProposal;
  violinAmount = violinProposal;
  transferTo(usd, usdAmount);
  transitionTo(:proposed);
}

@initial {charlie}
noDeal() {
  transitionTo(:terminal);
}

@proposed {charlie}
retract() {
  transferFrom(usd, usdAmount, charlie);
  transitionTo(:initial);
}

@proposed {david}
accept() {
  transferHoldings(david, violin, violinAmount, charlie);
  transferFrom(usd, usdAmount, david);
  transitionTo(:initial);
}

@proposed {david}
reject() {
  transferFrom(usd, usdAmount, charlie);
  transitionTo(:initial);
}