title: "RuntimeError: generator raised StopIteration" every time I try to run app
body: <p>I am trying to run this code:</p>
  
  <pre><code>import web
  
  urls = (
      '/', 'index'
  )
  
  if __name__ == "__main__":
      app = web.application(urls, globals())
      app.run()
  </code></pre>
  
  <p>But it gives me this error everytime</p>
  
  <pre><code>C:\Users\aidke\Desktop&gt;python app.py
  Traceback (most recent call last):
    File "C:\Users\aidke\AppData\Local\Programs\Python\Python37-32\lib\site-packages\web\utils.py", line 526, in take
      yield next(seq)
  StopIteration
  
  The above exception was the direct cause of the following exception:
  
  Traceback (most recent call last):
    File "app.py", line 14, in &lt;module&gt;
      app = web.application(urls, globals())
    File "C:\Users\aidke\AppData\Local\Programs\Python\Python37-32\lib\site-packages\web\application.py", line 62, in __init__
      self.init_mapping(mapping)
    File "C:\Users\aidke\AppData\Local\Programs\Python\Python37-32\lib\site-packages\web\application.py", line 130, in init_mapping
      self.mapping = list(utils.group(mapping, 2))
    File "C:\Users\aidke\AppData\Local\Programs\Python\Python37-32\lib\site-packages\web\utils.py", line 531, in group
      x = list(take(seq, size))
  RuntimeError: generator raised StopIteration
  </code></pre>
  
  <p>I tried someone else's code and the exact same thing happened.  Additionally I tried reinstalling web.py(experimental) but it still didn't work.</p>