code: def siblings(self):
          
          parent = self.parent
          if parent is None:
              return tuple()
          else:
              return tuple([node for node in parent.children if node != self])
docs: Tuple of nodes with the same parent.
  
          >>> from anytree import Node
          >>> udo = Node("Udo")
          >>> marc = Node("Marc", parent=udo)
          >>> lian = Node("Lian", parent=marc)
          >>> loui = Node("Loui", parent=marc)
          >>> lazy = Node("Lazy", parent=marc)
          >>> udo.siblings
          ()
          >>> marc.siblings
          ()
          >>> lian.siblings
          (Node('/Udo/Marc/Loui'), Node('/Udo/Marc/Lazy'))
          >>> loui.siblings
          (Node('/Udo/Marc/Lian'), Node('/Udo/Marc/Lazy'))