code: def set_child_node(self, name, node):
          
          assert isinstance(node, TreeMapNode)
          self._nodes[name] = node
          node.set_parent(self)
docs: Add one child node to this node.
  
          Args:
              name (str): Name of the child.
              node (TreeMapNode): Node to add.
  
          Warning:
              No test is done to see whether or not a node was already attached with that name. If this is the case, the
              new node takes the place of the old one that is now unreachable. See :meth:`set_unique_child_node`.