<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def values(self):
 """ Return the list of values. """

        def collect(d):
            if d is None or d.get('FIRST') is None:
                return []
            vals = [d['FIRST']]
            vals.extend(collect(d.get('REST')))
            return vals
        return collect(self)