title: AWSAppSync AWS defined scalar types - definitions?
body: <p>The <a href="https://docs.aws.amazon.com/appsync/latest/devguide/scalars.html" rel="nofollow noreferrer">AppSync docs</a> 
   describe some extended scalar types, e.g., AWSDateTime, but don't tell me the actual type definitions so I can use in my typescript client (an ionic app). I don't see the types anywhere in the <a href="https://github.com/aws/aws-sdk-js" rel="nofollow noreferrer">aws-sdk-js</a> or the <a href="https://github.com/awslabs/aws-mobile-appsync-sdk-js" rel="nofollow noreferrer">aws-appsync</a> packages - where would I find the definitions or some usage examples for typescript (in my client or lambda functions)?</p>