code: func CheckCertificate(c context.Context, cert *x509.Certificate) (*certconfig.CA, error) {
  	checker, err := GetCertChecker(c, cert.Issuer.CommonName)
  	if err != nil {
  		return nil, err
  	}
  	return checker.CheckCertificate(c, cert)
  }
docs: // CheckCertificate checks validity of a given certificate.
  //
  // It looks at the cert issuer, loads corresponding CertChecker and calls its
  // CheckCertificate method. See CertChecker.CheckCertificate documentation for
  // explanation of return values.