'Generates replication retention settings in Purity compatible format
An example of the settings:
target_all_for = 14400 (i.e. 4 hours)
target_per_day = 6
target_days = 4
The settings above configure the target array to retain 4 hours of
the most recent snapshots.
After the most recent 4 hours, the target will choose 4 snapshots
per day from the previous 6 days for retention
:return: a dictionary representing replication retention settings'

@pure_driver_debug_trace
def _generate_replication_retention(self):

    replication_retention = dict(target_all_for=self._replication_retention_short_term, target_per_day=self._replication_retention_long_term_per_day, target_days=self._replication_retention_long_term)
    return replication_retention
