Env returns the value for an enviroment variable or an error when it doesn't exist.

SetResponseBody marshals body into an APIGatewayProxyResponse body.

SetResponseMessage sets an APIGatewayProxyResponse body like {"message": "..."}.

Start calls github.com/aws/aws-lambda-go/lambda.Start.

Start calls github.com/aws/aws-lambda-go/lambda.StartHandler.