Reverting binder to xtensor 0.15.9 until gcc-7 package is fixed
Reverting binder to xtensor 0.15.9 until gcc-7 package is fixed

xtensor-stack/xtensor,QuantStack/xtensor,xtensor-stack/xtensor,JohanMabille/xtensor,QuantStack/xtensor,JohanMabille/xtensor