An Examples Folder

[KaviiSuri]

Is your feature request related to a problem? Please describe.
As someone exploring a library or a contributor, it can be messy to create a sandbox project to test out the local version.

I'm not sure if this is worth maintaining, but I just wanted to propose the idea.

Describe the solution you'd like
An example folder, similar to how it's done in the webpush-go package can solve this easily.

The example folder may contain examples for each type service, with the required setup code.

[AboutSange]

Yes, I agree, An example folder is very useful.
The example folder structure could be like this:

service/
    mail/
        example/
            example.go
        mail.go
        mail_test.go
        README.go

And example.go could be like this:

package main

func main() {
...
}

And then we can run go run example.go directly for real test.