code: func builtinJWTVerify(a ast.Value, b ast.Value, verify func(publicKey interface{}, digest []byte, signature []byte) error) (ast.Value, error) {
  	// Decode the JSON Web Token
  	token, err := decodeJWT(a)
  	if err != nil {
  		return nil, err
  	}
  
  	// Process PEM encoded certificate input
  	astCertificate, err := builtins.StringOperand(b, 2)
  	if err != nil {
  		return nil, err
  	}
  	key, err := getKeyFromCert(string(astCertificate))
  	if err != nil {
  		return nil, err
  	}
  
  	signature, err := token.decodeSignature()
  	if err != nil {
  		return nil, err
  	}
  
  	// Validate the JWT signature
  	err = verify(key,
  		getInputSHA([]byte(token.header+"."+token.payload)),
  		[]byte(signature))
  
  	if err != nil {
  		return ast.Boolean(false), nil
  	}
  	return ast.Boolean(true), nil
  }
docs: // Implements JWT signature verification.