if _, found := result[key]; !found {
			result[key] = value.DeepCopy()
		}
	}
	return result
}

// SubtractWithNonNegativeResult - subtracts and returns result of a - b but
// makes sure we don't return negative values to prevent negative resource usage.
func SubtractWithNonNegativeResult(a corev1.ResourceList, b corev1.ResourceList) corev1.ResourceList {
	zero := resource.MustParse("0")

		if err == nil && len(metadata.GetResourceVersion()) > 0 {
			prevUsage, innerErr := evaluator.Usage(prevItem)
			if innerErr != nil {
				return quotas, innerErr
			}
			deltaUsage = quota.SubtractWithNonNegativeResult(deltaUsage, prevUsage)
		}
	}

	// ignore items in deltaUsage with zero usage
	deltaUsage = quota.RemoveZeros(deltaUsage)
	// if there is no remaining non-zero usage, short-circuit and return