Can't use APIGatewayProxyRequest and APIGatewayProxyResponse #7

I try to implement from your solution in https://medium.com/@zaccharles/hi-bofei-cao-9b66d27d8afa but it's not work

and try to use this solution

byte[] byteArray = Encoding.UTF8.GetBytes(input);
MemoryStream stream = new MemoryStream(byteArray);
APIGatewayProxyRequest request = Serializer.Deserialize<APIGatewayProxyRequest>(stream);

it's not work too.

because I can't get anything with "request" such as I get request.PathParameters.ContainsKey("var_name") . I got a timeout message