let() is define a memoized method. When you inherit or include that module into a new class, you can redefine that same let() and the new class will use the red

let() is define a memoized method. When you inherit or include that module into a new class, you can redefine that same let() and the new class will use the redefined method instead of what is inherited. You can do that with any of the let() that gets defined. This lets you use as much or as little of the shared code that you want.