title: Invoke AWS Lambda and return response to API Gateway asyncronously
body: <p>My use case is such that I'll have an AWS Lambda front ended with API Gateway.</p>
  
  <p>My requirement is that once the Lambda is invoked it should return a 200 OK response back to API Gateway which get forwards this to the caller.
  And then the Lambda should start its actual processing of the payload.</p>
  
  <p>The reason for this is that the API Gateway caller service expects a response within 10 seconds else it times out. So I want to give the response before I start with the processing.</p>
  
  <p>Is this possible?</p>