Challenge 3: extend for a Class-Level Method — Solution

module Describable
  def describe
    "This is the #{name} class"
  end
end

class Product
  extend Describable
end

puts Product.describe

=begin
Output:
This is the Product class

Notes:
- extend Describable mixes describe in as a CLASS method, not an instance
  method — it becomes available on Product itself, not on Product.new.
- Product.describe is called directly on the class, with no instance
  created at all, which is the key difference from Challenge 1 and 2's
  include (where the method only became available on instances).
- Inside describe, name refers to the class's own name (a built-in Ruby
  method that returns "Product" here) — this only works because describe
  is running in the context of the class itself, which is exactly what
  extend arranges for.
=end