# File lib/merb-mailer/mailer.rb, line 85
    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 do |v|
          if v.length < 2
            v << v.first.is_a?(File) ? File.basename(v.first.path) : nil
          end
          @mail.add_attachment_as *v
        end
      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