setup_dirs (Multiruby)

    # File lib/multiruby.rb, line 304
      def self.setup_dirs download = true
        %w(build install versions tmp).each do |dir|
          unless test ?d, dir then
            puts "creating #{dir}"
            Dir.mkdir dir
            if dir == "versions" && download then
              warn "  Downloading initial ruby tarballs to ~/.multiruby/versions:"
              VERSIONS.each do |v|
                self.fetch_tar v
              end
              warn "  ...done"
              warn "  Put other ruby tarballs in ~/.multiruby/versions to use them."
            end
          end
        end
      end