def handle_state(flow, old_state, new_state):
    def param_value_for(param_name, state):
        p = next(filter(lambda k: k.name == param_name, new_state.result.keys()))
        r = state.result[p]
        return r.result

    if new_state.is_running():
        foo = param_value_for('foo', new_state)
        print('Starting to run')
    elif new_state.is_failed():
        foo = param_value_for('foo', new_state)
        print(f'We have a failure for {foo}')
    elif new_state.is_successful():
        foo = param_value_for('foo', new_state)
        print(f'We have a success for {foo}')