Aws Lambda and websockets. Getting UnknownServiceError: Unknown service: 'apigatewaymanagementapi'. Not supported yet?

Anyone knows why this is not supported on AWS lambda? To my knowledge the boto3 version is 1.10. And the 1.9 docu says it should be there. Anyone know anything about it?
M

I tried using Node.js run-time in the AWS Lambda and was able to send messages using websocket from Lambda. Check this link (https://medium.freecodecamp.org/real-time-applications-using-websockets-with-aws-api-gateway-and-lambda-a5bb493e9452)

And also tried using boto3(python run-time) but getting the same error as u faced. Let me know if you have achieved using boto3 in AWS Lambda.