code: def is_child(self, node):
          
          if node in self.children:
              return True
          for c in self.children:
              if c.is_child(node):
                  return True
          return False
docs: Check if a node is a child of the current node
  
          Parameters
          ----------
          node : instance of Node
              The potential child.
  
          Returns
          -------
          child : bool
              Whether or not the node is a child.