using aws lambda code example

Example 1: why aws lambda is called lambda

In programming, a Lambda expression (or function) is just an anonymous function, i.e., a function with no name.

Example 2: aws lambda tutorial

callback();                // It will return success, but no indication to the caller
callback(null);            // It will return success, but no indication to the caller
callback(null, "success"); // It will return the success indication to the caller
callback(error);           //  It will return the error indication to the caller