title: How to properly navigate an NLTK parse tree?
body: <p>NLTK is driving me nuts again.</p>
  
  <p>How do I properly navigate through an NLTK tree (or ParentedTree)?
  I would like to identify a certain leaf with the parent node "VBZ", then I would like to move from there further up the tree and to the left to identify the NP node.</p>
  
  <p>How do I do this? The NLTK tree class does not seem to be thought through... Or I am too stupid...</p>
  
  <p>Thanks for your help!</p>
  
  <p><img src="https://i.stack.imgur.com/a1ANO.png" alt="Tree"></p>