<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def data(self):
 """return dictionary with data. If data entries are None or incomplete, consider calling ``.load().data()`` to (re-)load the data from files first. """

        d = {}
        for name in self.key_names:
            d[name] = self.__dict__.get(name, None)
        return d