code_meta_analysis.js

RandomService.formatPayload = function (id, fn) {
/* Should deduce that RandomService is an object, has a property named 'formatPayload'
a funtion with two arguments is being expressed on the property, so it's a method */

	return {
	// this method returns an object

		client_id: id,
		/* returned object has a property 'client_id', which has the id argument as value or a reference
		we cannot deduce the type of the 'id' argument
		could be a primitive or an object */

		body: fn().data
		/* returned object has a property 'body'
		which has the property 'data' of the result of the called fn argument as a value or a reference
		We know for sure now fn is a callback that should return an object with data as a propery
		but we cannot deduce the type of 'data'*/
	}
}

RandomService.formatPayload("AZER1234", () => {
	/* the method is now being called.
	first argument is a string which is ok cause it could have any type
	the secound argument is an expressed callback which is what was expected */

	const result = {
	/* result is being declared as an oject in the context of RandomService
  cause we are using an arrow function */
		status_code: 200,
		data: {
			name: "Mario",
			profession: "plumber"
		}
	}

	// callback ends without returning anything
})
/* this code should throw an error "Cannot read property 'data' of undefined"
Cause the callback don't return anything*/