code: def add_children(self, root):
          
          for c in root.getChildren(ns=wsdlns):
              child = Factory.create(c, self)
              if child is None:
                  continue
              self.children.append(child)
              if isinstance(child, Import):
                  self.imports.append(child)
                  continue
              if isinstance(child, Types):
                  self.types.append(child)
                  continue
              if isinstance(child, Message):
                  self.messages[child.qname] = child
                  continue
              if isinstance(child, PortType):
                  self.port_types[child.qname] = child
                  continue
              if isinstance(child, Binding):
                  self.bindings[child.qname] = child
                  continue
              if isinstance(child, Service):
                  self.services.append(child)
                  continue
docs: Add child objects using the factory