tree_implementation

class BinaryTree:
    def __init__(self, root_val):
        self.root = root_val
        self.left = None
        self.right = None
        
    def insert_left(self, node):
        if self.left is None:
            self.left = BinaryTree(node)
        else:
            t = BinaryTree(node)
            t.left = self.left
            self.left = t
            
    def insert_right(self, node):
        if self.right is None:
            self.right = BinaryTree(node)
        else:
            t = BinaryTree(node)
            t.right = self.right
            self.right = t
    
    def set_root_val(self, val):
        self.root = val
    
    def get_root_val(self):
        return self.root
    
    def get_left_child(self):
        return self.left
    
    def get_right_child(self):
        return self.right
    
    def __str__(self, level=0):
        s = '\t'*level + str(self.root) + '\n'
        if self.left is not None:
            s += self.left.__str__(level+1)
        else:
            s += '\t'*(level+1) + 'None\n'
            
        if self.right is not None:
            s += self.right.__str__(level+1)
        else:
            s += '\t'*(level+1) + 'None\n'
        
        return s