code: func CertAuthoritiesToV1(in []CertAuthority) ([]CertAuthorityV1, error) {
  	out := make([]CertAuthorityV1, len(in))
  	type cav1 interface {
  		V1() *CertAuthorityV1
  	}
  	for i, ca := range in {
  		v1, ok := ca.(cav1)
  		if !ok {
  			return nil, trace.BadParameter("could not transform object to V1")
  		}
  		out[i] = *(v1.V1())
  	}
  	return out, nil
  }
docs: // CertAuthoritiesToV1 converts list of cert authorities to V1 slice