# File lib/uri/common.rb, line 280
    def escape(str, unsafe = UNSAFE)
      unless unsafe.kind_of?(Regexp)
        # perhaps unsafe is String object
        unsafe = Regexp.new(Regexp.quote(unsafe), false, 'N')
      end
      str.gsub(unsafe) do |us|
        tmp = ''
        us.each_byte do |uc|
          tmp << sprintf('%%%02X', uc)
        end
        tmp
      end
    end