sample_group_map_iterator sample_grp_current = _sample_groups.begin();
sample_group_map_iterator sample_grp_end = _sample_groups.end();
for ( ; sample_grp_current != sample_grp_end; ++sample_grp_current ) {
sample_group_map_iterator sample_grp_current = _sample_groups.begin();
sample_group_map_iterator sample_grp_end = _sample_groups.end();
for ( ; sample_grp_current != sample_grp_end; ++sample_grp_current ) {