title: parse(text) - AttributeError: 'str' object has no attribute 'unknown'
body: <p>Could anyone shed any light on why I am receiving this error? I am new to using 'pattern' and have the following code in my python file:</p>
  <pre><code>from pattern.en import parse
  from pattern.en import pprint
  
  pprint(parse('I drove my car to the hospital yesterday', relations=True, lemmata=True))
  </code></pre>
  <p>I have followed the instructions as mentioned on this tutorial: <a href="https://stackabuse.com/python-for-nlp-introduction-to-the-pattern-library/" rel="nofollow noreferrer">https://stackabuse.com/python-for-nlp-introduction-to-the-pattern-library/</a></p>
  <p>Does anyone know why I keep getting this error? It happens when calling the <em>parse</em> method. The error happens in the file <em>pattern/text/<strong>init</strong>.py</em> and the line of code which is throwing this error is <code>if tag is None or token in (model is not None and model.unknown or ()):</code> on line 1516. This code also exists on GitHub which suggests that it's not a mistake and should be coded like this. I can't find any answers to this problem anywhere online and feel completely stuck knowing what to do.</p>
  <p>I am running this with <em>python3.6</em> which is known to be compatible with the <em>pattern</em> module.</p>
  <p>If you know what the problem is and how to solve it then I would be most grateful!</p>