code: def get_schema_descendant(
              self, route: SchemaRoute) -> Optional[SchemaNode]:
          
          node = self
          for p in route:
              node = node.get_child(*p)
              if node is None:
                  return None
          return node
docs: Return descendant schema node or ``None`` if not found.
  
          Args:
              route: Schema route to the descendant node
                     (relative to the receiver).