SamReadGroupConstIterator begin = ConstBegin();
SamReadGroupConstIterator iter = begin;
SamReadGroupConstIterator end = ConstEnd();
for ( ; iter != end; ++iter ) {
SamReadGroupConstIterator begin = ConstBegin();
SamReadGroupConstIterator iter = begin;
SamReadGroupConstIterator end = ConstEnd();
for ( ; iter != end; ++iter ) {