def returnValueList(self, key_list, last=False):
        '''Return a list of key values for the first entry in the current list.
        If 'last=True', then the last entry is referenced."
        Returns None is the list is empty. If a key is missing, then
        that entry in the list is None.
        Example of use:
        >>> test = [
        ...    {"name": "Jim",   "age": 18, "income": 93000, "order": 2},
        ...    {"name": "Larry", "age": 18,                  "order": 3},
        ...    {"name": "Joe",   "age": 20, "income": 15000, "order": 1},
        ...    {"name": "Bill",  "age": 19, "income": 29000, "order": 4},
        ... ]
        >>> print PLOD(test).returnValueList(["name", "income"])
        ['Jim', 93000]
        >>> print PLOD(test).sort("name").returnValueList(["name", "income"], last=True)
        ['Larry', None]
        :param last:
           If True, the last entry is used rather than the first.
        :return:
           A value, or None if the list is empty.
        '''
        result = []
        row = self.returnOneEntry(last=last)
        if not row:
            return None
        dict_row = internal.convert_to_dict(row)
        for field in key_list:
            result.append(dict_row.get(field, None))
        return result