get_one_gem_name (Gem::Command)

    # File lib/rubygems/command.rb, line 76
        def get_one_gem_name
          args = options[:args]

          if args.nil? or args.empty? then
            raise Gem::CommandLineError,
                 "Please specify a gem name on the command line (e.g. gem build GEMNAME)"
          end

          if args.size > 1 then
            raise Gem::CommandLineError,
                  "Too many gem names (#{args.join(', ')}); please specify only one"
          end

          args.first
        end