    # File lib/chef/knife.rb, line 119
        def self.subcommands_by_category
          unless @subcommands_by_category
            @subcommands_by_category = Hash.new { |hash, key| hash[key] = [] }
            subcommands.each do |snake_cased, klass|
              @subcommands_by_category[klass.subcommand_category] << snake_cased
            end
          end
          @subcommands_by_category
        end