public Result AddMethodsToExperiment(AddMethodsToExperiment addMethodsToExperiment) { //Will fail if the experiment does not exist long experimentId = addMethodsToExperiment.ExperimentId; List <long> methodsIds = addMethodsToExperiment.MethodsIds; Experiment experiment = experimentsMemoryDatabase.SingleOrDefault(e => e.Id == experimentId); if (experiment == null) { return(Result.Fail("The provided experiment does not exist")); } methodsIds.ForEach(mId => experiment.AddMethod(mId)); return(Result.Ok()); }