Make a copy of the Quantity before storing in the cache
Make a copy of the Quantity before storing in the cache

Quantity objects are mutable, an therefore can be changed in place
 >> q += other
When q is stored in the feat cache, the value of the cache can
be modified without changing the Feat.

LabPy/lantz,LabPy/lantz_qt,LabPy/lantz_qt,LabPy/lantz_qt,LabPy/lantz,LabPy/lantz,varses/awsch,varses/awsch,LabPy/lantz