Rails: I can’t call a function in a module in /lib – what am I doing wrong?

If you want Module-level functions, define them in any of these ways:

module Foo
  def self.method_one
  end

  def Foo.method_two
  end

  class << self
    def method_three
    end
  end
end

All of these ways will make the methods available as Foo.method_one or Foo::method_one etc

As other people have mentioned, instance methods in Modules are the methods which are available in places where you’ve included the Module