usage_message (RubiGen::Scripts::Destroy)

    # File lib/rubigen/scripts/destroy.rb, line 8
        def usage_message
          usage = "\nInstalled Generators\n"
          RubiGen::Base.sources.each do |source|
            label = source.label.to_s.capitalize
            names = source.names
            usage << "  #{label}: #{names.join(', ')}\n" unless names.empty?
          end

          # TODO - extensible blurbs for rails/newgem/adhearsion etc
          # e.g. for rails script/destroy
          # http://github.com/rails/rails/tree/daee6fd92ac16878f6806c3382a9e74592aa9656/railties/lib/rails_generator/scripts/destroy.rb
          usage << "\nThis script will destroy all files created by the corresponding\nscript/generate command. For instance, script/destroy test_unit create_post\nwill delete the appropriate test_create_post.rb file in /test.\n\nFor instructions on finding new generators, run script/generate\n"
          return usage
        end