Good point.

Most likely, the "sub getObservations{}" modifies $_ , which would upset the values in the "map" case, where he uses "$_->getObservations() ".

In the "for" loop, he uses "$docP->" as the alias for the values, so modifying $_ inside "sub getObservations" will not change the values.

The fix would be to "local $_" inside "sub getObservations{}" where necessary.