Chaining ember promises in coffeescript

gistfile1.txt

addProblem: (disease) ->
      Ordering.MedicalRecord.store.find("medicalRecord",2)
      .then (mr) =>
        mr.get("problems")
        .then (problems) =>
          o = @store.createRecord("problem", {disease: disease, medicalRecord: mr})
      .then (p) ->
        p.save().then ->
          console.log "Problem was saved correctly!"