title: PyQT and QTreeView: Need to ask for childrens when user clicks on an item
body: <p>I need to create a QTreeView based on requests.</p>
  
  <p>So, when the user open the application, it should make a request to get the root item for the tree. Once the user clicks on that item, it should ask for the children, and so on.</p>
  
  <p>I couldn't find any working example with requests as I want and I don't even know if this is possible.</p>