code: func (s *inMemoryStore) Get(ctx context.Context, h types.Metric, resetTime time.Time, fieldVals []interface{}) interface{} {
  	if resetTime.IsZero() {
  		resetTime = clock.Now(ctx)
  	}
  
  	m := s.getOrCreateData(h)
  	m.lock.Lock()
  	defer m.lock.Unlock()
  
  	return m.get(fieldVals, target.Get(ctx), resetTime).Value
  }
docs: // Get returns the value for a given metric cell.