Why does this not return anything after running it? class BSTnode:     def __init__(self, key=None, left=None, right=None, parent=None):         # Initialize a node.         self.__key = key  # value for the node         self.__left = left         self.__right = right         self.__parent = parent     def setkey(self, newkey):         # Sets the key value of the node to newkey         self.__key = newkey     def getkey(self):         # returns the key value of the node         return self.__key     def getright(self):         # returns the right child of the node         return self.__right     def setright(self, newright):         # Sets the right child to the new node object newright. Child nodes parent is also updated.         self.__right = newright         if newright is not None:             newright.__parent = self     def getleft(self):         # returns the left child of the node.         return self.__left     def setleft(self, newleft):         # Sets the left child to the new node object newleft. Child nodes parent is also updated.         self.__left = newleft         if newleft is not None:             newleft.__parent = self     def getparent(self):         # returns the parent of the node         return self.__parent     def setparent(self, newparent, left=True):         # Sets the parent to the new node object newparent.         # Parents child pointer is also updated based on the value of the left.         # If left = True then sets node as left child of parent, sets as right child otherwise.         self.__parent = newparent         if newparent is not None:             if left:                 newparent.__left = self             else:                 newparent.__right = self class BST:     def __init__(self, root=None):         if root is not None:             root.setparent(None)         self.__root = root     def getroot(self):         # Returns the root node of the tree         return self.__root     def setroot(self, node):         # Sets the root node of the tree         self.__root = node     def insertnode(self, node):         # Inserts a node to the correct position in a BST. A success returns true and failure returns false.         if self.__root is None:             self.__root = node             return True         else:             currentnode = self.__root             while True:                 if node.getkey() == currentnode.getkey():                     return False                 elif node.getkey() < currentnode.getkey():                     if currentnode.getleftchild() is None:                         currentnode.setleftchild(node)                         node.setparent(currentnode)                         return True                     else:                         currentnode = currentnode.getleftchild()                 else:                     if currentnode.getrightchild() is None:                         currentnode.setrightchild(node)                         node.setparent(currentnode)                         return True                     else:                         currentnode = currentnode.getrightchild()     def searchnode(self, searchkey):         # Search the BST for a node with searchkey. If found returns the first node with searchkey and failure returns false.         currentnode = self.__root         while currentnode is not None:             if searchkey == currentnode.getkey():                 return currentnode             elif searchkey < currentnode.getkey():                 currentnode = currentnode.getleftchild()             else:                 currentnode = currentnode.getrightchild()         return False     def __removenode(self, node):         # Removes a node from the BST. This method uses the __successornode and __replacechild method.         if node.getleftchild() is None and node.getrightchild() is None:             parentnode = node.getparent()             if parentnode is None:                 self.__root = None             else:                 if node == parentnode.getleftchild():                     parentnode.setleftchild(None)                 else:                     parentnode.setrightchild(None)         elif node.getleftchild() is None:             self.__replacechild(node.getparent(), node, node.getrightchild())         elif node.getrightchild() is None:             self.__replacechild(node.getparent(), node, node.getleftchild())         else:             successor = self.__successornode(node)             if successor != node.getrightchild():                 self.__replacechild(successor.getparent(), successor, successor.getrightchild())                 successor.setrightchild(node.getrightchild())                 node.getrightchild().setparent(successor) tree = BST() # Insert some nodes node1 = BSTnode(5) node2 = BSTnode(3) node3 = BSTnode(7) tree.insertnode(node1) tree.insertnode(node2) tree.insertnode(node3) tree.getroot()