func (pm *VolumePluginMgr) FindExpandablePluginBySpec(spec *Spec) (ExpandableVolumePlugin, error) {
	volumePlugin, err := pm.FindPluginBySpec(spec)
	if err != nil {
		if spec.IsKubeletExpandable() {
			// for kubelet expandable volumes, return a noop plugin that
			// returns success for expand on the controller
			klog.V(4).InfoS("FindExpandablePluginBySpec -> returning noopExpandableVolumePluginInstance", "specName", spec.Name())

	// giving 00000110b (0x06) and 00011111b (0x1f).
	// [1] http://csrc.nist.gov/publications/drafts/fips-202/fips_202_draft.pdf
	//     "Draft FIPS 202: SHA-3 Standard: Permutation-Based Hash and
	//      Extendable-Output Functions (May 2014)"
	dsbyte byte

	i, n    int // storage[i:n] is the buffer, i is only used while squeezing
	storage [maxRate]byte

	// Specific to SHA-3 and SHAKE.