code: def visit_and_update(self, visitor_fn):
          
          new_left = self.left.visit_and_update(visitor_fn)
          new_right = self.right.visit_and_update(visitor_fn)
  
          if new_left is not self.left or new_right is not self.right:
              return visitor_fn(BinaryComposition(self.operator, new_left, new_right))
          else:
              return visitor_fn(self)
docs: Create an updated version (if needed) of BinaryComposition via the visitor pattern.