<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_db_prep_save(self, value, connection, prepared=False):
 """ Convert Python value to database value for SAVING. We save with full timezone information. """

        log.debug("get_db_prep_save: {}, {}", value, type(value))
        if not value:
            return ''
            # For underlying (database) string types, e.g. VARCHAR, this
            # function must always return a string type.
            # https://docs.djangoproject.com/en/1.8/howto/custom-model-fields/
        return python_localized_datetime_to_human_iso(value)