title: python: getting keys of a dictionary
body: <p>When I do dict.keys() in python3, I do not get a list, but an object of class dict_keys. Why is this and what can I do with this object? How to get the list?</p>
  
  <p>Example code: <code>type(dict(sape=4139, guido=4127, jack=4098).keys())</code>
  I wonder if this result is intentional and why?
  I called matplotlib.plot(d.keys(),....) and got an error.</p>