Illustrates that a method can contain a method definition, but that the inner defined method becomes a regular instance method, rendering the code nesting misleading.

inner_method.rb

#!/usr/bin/env ruby

class C
  def foo
    def bar
      puts "I am bar."
    end
    bar
  end
end
# nil

c = C.new

c.foo
# I am bar.

c.bar
# I am bar.

puts C.public_instance_methods.include?(:bar)
# true