code: func IsVolumeBoundToClaim(volume *v1.PersistentVolume, claim *v1.PersistentVolumeClaim) bool {
  	if volume.Spec.ClaimRef == nil {
  		return false
  	}
  	if claim.Name != volume.Spec.ClaimRef.Name || claim.Namespace != volume.Spec.ClaimRef.Namespace {
  		return false
  	}
  	if volume.Spec.ClaimRef.UID != "" && claim.UID != volume.Spec.ClaimRef.UID {
  		return false
  	}
  	return true
  }
docs: // IsVolumeBoundToClaim returns true, if given volume is pre-bound or bound
  // to specific claim. Both claim.Name and claim.Namespace must be equal.
  // If claim.UID is present in volume.Spec.ClaimRef, it must be equal too.