utils: add `ndenumerate` utility function
utils: add `ndenumerate` utility function

g-weatherill/oq-risklib,gem/oq-engine,raoanirudh/oq-risklib,vup1120/oq-risklib,raoanirudh/oq-risklib,gem/oq-engine,g-weatherill/oq-risklib,gem/oq-engine,vup1120/oq-risklib,gem/oq-engine,g-weatherill/oq-risklib,gem/oq-engine