{"ns":"test.coll","op":"command","command":{"mapreduce":"coll","map":{"code":"function () {\n    emit(this.a, this.b);\n}"},"reduce":{"code":"function (a, b) {\n    return Array.sum(b);\n}"},"query":{"a":{"$gte":0}},"out":{"inline":1},"$db":"test"}}