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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_field(self, field, idx=None, astype=None):
 """ Return `self.field` for the elements labeled by `idx` :param astype: type cast of the return value :param field: field name of this model :param idx: element indices, will be the whole list if not specified :return: field values """

        assert astype in (None, list, matrix)
        ret = None

        if idx is None:
            idx = self.idx

        # ===================disable warning ==============================
        # if field in self._service:
        # logger.warning(
        #     'Reading service variable <{model}.{field}> could be unsafe.'
        #         .format(field=field, model=self._name)
        # )
        # =================================================================

        uid = self.get_uid(idx)

        field_data = self.__dict__[field]

        if isinstance(field_data, matrix):
            ret = field_data[uid]
        elif isinstance(field_data, list):
            if isinstance(idx, (float, int, str)):
                ret = field_data[uid]
            else:
                ret = [field_data[x] for x in uid]

        if astype is not None:
            ret = astype(ret)

        return ret