public void addExercise(String name, List<SetModel> list_of_sets) {
   ExerciseModel exercise = new ExerciseModel();
   exercise.setName(name);
   exercise.setSets(list_of_sets);
   mExercises.add(exercise);
 }
 @Override
 public void onBindViewHolder(ExerciseAdapter.ViewHolder holder, int position) {
   ExerciseModel tmpExercise = mExercises.get(position);
   holder.mExerciseName.setText(tmpExercise.getName());
   holder.mSets.setText("Sets: " + tmpExercise.getSets().size());
 }