code: func (p *Provider) GetTLSALPNCertificate(domain string) (*tls.Certificate, error) {
  	cert, err := p.Store.GetTLSChallenge(domain)
  	if err != nil {
  		return nil, err
  	}
  
  	if cert == nil {
  		return nil, nil
  	}
  
  	certificate, err := tls.X509KeyPair(cert.Certificate, cert.Key)
  	if err != nil {
  		return nil, err
  	}
  
  	return &certificate, nil
  }
docs: // GetTLSALPNCertificate Get the temp certificate for ACME TLS-ALPN-O1 challenge.