A simple lambda function contains the following data:-
START RequestId:  
Version: $LATEST
The message from the function to be printed, i.e. event{'key1': 'This will be printed in logs'}
END RequestId: 
REPORT RequestId: 
Duration: time in ms
Billed Duration: 100 ms
Memory Size: 128 MB
Max Memory Used: 20 MB
Hope this helps