code: func (id *identity) GetOrganizationalUnits() []*OUIdentifier {
  	if id.cert == nil {
  		return nil
  	}
  
  	cid, err := id.msp.getCertificationChainIdentifier(id)
  	if err != nil {
  		mspIdentityLogger.Errorf("Failed getting certification chain identifier for [%v]: [%+v]", id, err)
  
  		return nil
  	}
  
  	res := []*OUIdentifier{}
  	for _, unit := range id.cert.Subject.OrganizationalUnit {
  		res = append(res, &OUIdentifier{
  			OrganizationalUnitIdentifier: unit,
  			CertifiersIdentifier:         cid,
  		})
  	}
  
  	return res
  }
docs: // GetOrganizationalUnits returns the OU for this instance