Use module_function for module functions.
Use module_function for module functions.

Explicitly defining singleton methods on a module is a perfectly
reasonable thing to do, but if you've got more than two or three, it's
arguably time to open its singleton class and define them there.

```ruby
class << self # (Quickstrings)
  def fname
  end

  def email
  end
end
```

That's one approach, but then everything gets pushed to the right a bit.
`module_function` is a convenient "visibility modifier" which specifies
that all subsequently defined methods should go on the receiver's
singleton class (unless and until another modifier is encountered).

C4mz0r/quickstrings,C4mz0r/quickstrings