# File lib/cgi.rb, line 1196
    def [](key)
      params = @params[key]
      return '' unless params
      value = params[0]
      if @multipart
        if value
          return value
        elsif defined? StringIO
          StringIO.new("")
        else
          Tempfile.new("CGI")
        end
      else
        str = if value then value.dup else "" end
        str
      end
    end