Added doctest
Added doctest


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Former-commit-id: d5707df2e2cbefcbe646082d8308603418c52aeb
Former-commit-id: 5a4e63e4fb0816f0e24168c0e7fca308bc6f4e05
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine