'Creates the following structure:
+ P1
| + P2
|   + P3
+ P4'

def create_some_pages(self):

    self.page1 = create_page('page1', 'nav_playground.html', 'en', published=True, in_navigation=True)
    self.page2 = create_page('page2', 'nav_playground.html', 'en', parent=self.page1, published=True, in_navigation=True)
    self.page3 = create_page('page3', 'nav_playground.html', 'en', parent=self.page2, published=True, in_navigation=True)
    self.page4 = create_page('page4', 'nav_playground.html', 'en', published=True, in_navigation=True)
    self.all_pages = [self.page1, self.page2, self.page3, self.page4]
    self.top_level_pages = [self.page1, self.page4]
    self.level1_pages = [self.page2]
    self.level2_pages = [self.page3]
