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db.collection.find({"levels.modules.module_id":"C1L2M1"},{_id:0,module:{$first:{$filter:{input:{$map:{input:"$levels",as:"l",in:{$first:{$filter:{input:"$$l.modules",as:"m",cond:{$eq:["$$m.module_id","C1L2M1"]}}}}}},as:"x",cond:{$ne:["$$x",null]}}}}})