# File lib/merb-mailer/mailer.rb, line 83
    def attach(file_or_files, filename = file_or_files.is_a?(File) ? File.basename(file_or_files.path) : nil, 
      type = nil, headers = nil)
      if file_or_files.is_a?(Array)
        file_or_files.each {|k,v| @mail.add_attachment_as k, *v}
      else
        raise ArgumentError, "You did not pass in a file. Instead, you sent a #{file_or_files.class}" if !file_or_files.is_a?(File)
        @mail.add_attachment_as(file_or_files, filename, type, headers)
      end
    end