title: pytube: AttributeError: 'NoneType' object has no attribute 'span'
body: <p>I just downloaded pytube (version 11.0.1) and started with this code snippet from <a href="https://pytube.io/en/latest/" rel="noreferrer">here</a>:</p>
  <pre><code>from pytube import YouTube
  YouTube('https://youtu.be/9bZkp7q19f0').streams.first().download()
  </code></pre>
  <p>which gives this error:</p>
  <pre><code>AttributeError                            Traceback (most recent call last)
  &lt;ipython-input-29-0bfa08b87614&gt; in &lt;module&gt;
  ----&gt; 1 YouTube('https://youtu.be/9bZkp7q19f0').streams.first().download()
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/__main__.py in streams(self)
      290         &quot;&quot;&quot;
      291         self.check_availability()
  --&gt; 292         return StreamQuery(self.fmt_streams)
      293 
      294     @property
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/__main__.py in fmt_streams(self)
      175         # https://github.com/pytube/pytube/issues/1054
      176         try:
  --&gt; 177             extract.apply_signature(stream_manifest, self.vid_info, self.js)                                                                            
      178         except exceptions.ExtractError:
      179             # To force an update to the js file, we clear the cache and retry                                                                           
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/extract.py in apply_signature(stream_manifest, vid_info, js)                                                     
      407 
      408     &quot;&quot;&quot;
  --&gt; 409     cipher = Cipher(js=js)
      410 
      411     for i, stream in enumerate(stream_manifest):
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/cipher.py in __init__(self, js)
       42 
       43         self.throttling_plan = get_throttling_plan(js)
  ---&gt; 44         self.throttling_array = get_throttling_function_array(js)
       45 
       46         self.calculated_n = None
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/cipher.py in get_throttling_function_array(js)                                                                   
      321 
      322     array_raw = find_object_from_startpoint(raw_code, match.span()[1] - 1)                                                                              
  --&gt; 323     str_array = throttling_array_split(array_raw)
      324 
      325     converted_array = []
  
  ~/anaconda3/lib/python3.8/site-packages/pytube/parser.py in throttling_array_split(js_array)                                                                    
      156             # Handle functions separately. These can contain commas
      157             match = func_regex.search(curr_substring)
  --&gt; 158             match_start, match_end = match.span()
      159 
      160             function_text = find_object_from_startpoint(curr_substring, match.span()[1])
  
  AttributeError: 'NoneType' object has no attribute 'span'
  </code></pre>
  <p>and I wonder why? Can anyone help me? I am running this snippet in an ipython console (IPython version 7.22.0) with Python 3.8.8 in a conda environment.</p>