title: findall() missing 1 required positional argument: 'string'
body: <p>I am trying to make a filter that when the user mention users, I try to open this accounts that have <code>@</code> For Example, if there are <code>@Users</code> this mention convert to link like Twitter.</p>
  <p>My Filter That raise this error <code>'findall() missing 1 required positional argument: 'string''</code></p>
  <pre><code> import re
  
  from django import template
  register = template.Library()
  def open_account(text):
      def open_account(text):
        results = re.findall(&quot;(^|[^@\w])@(\w{1,20})&quot;)
        for result in results:
          result = result[0]
        return text.replace(result, '&lt;a target=&quot;_blank&quot; style=&quot;color: blue;&quot;')
  
  
  url_target_blank = register.filter(open_account, is_safe = True)
  </code></pre>