old_contents: from wheelcms_axle.models import type_registry
  
  class Toolbar(object):
      """
          Wrap toolbar-related data, functionality
      """
      def __init__(self, instance, status="view"):
          self.instance = instance
          self.status = status
  
      def type(self):
          if not self.instance.content():
              return None
  
          return type_registry.get(self.instance.content().meta_type)
  
      def children(self):
          type = self.type()
          ## order?
          ## unconnected, or no restrictions
          if type is None or type.children is None:
              ch = type_registry.values()
          else:
              ch = type.children
  
          return [dict(name=c.name()) for c in ch]
  
      def show_create(self):
          if self.status == 'create':
              return False
          if self.type() is None:
              return True
          if self.type().children is None:
              return True
          return bool(self.type().children)
  
new_contents: from wheelcms_axle.models import type_registry
  
  class Toolbar(object):
      """
          Wrap toolbar-related data, functionality
      """
      def __init__(self, instance, status="view"):
          self.instance = instance
          self.status = status
  
      def type(self):
          if not self.instance.content():
              return None
  
          return type_registry.get(self.instance.content().meta_type)
  
      def children(self):
          type = self.type()
          ## order?
          ## unconnected, or no restrictions
          if type is None:
              ch = type_registry.values()
          else:
              ch = type.addable_children()
  
          return [dict(name=c.name()) for c in ch]
  
      def show_create(self):
          if self.status == 'create':
              return False
          if self.type() is None:
              return True
          if self.type().children is None:
              return True
          return bool(self.type().children)
  
subject: implement implicit/explicit addability - #506