code: def _aside_from_xml(self, node, block_def_id, block_usage_id, id_generator):
          
          id_generator = id_generator or self.id_generator
  
          aside_type = node.tag
          aside_class = self.load_aside_type(aside_type)
          aside_def_id, aside_usage_id = id_generator.create_aside(block_def_id, block_usage_id, aside_type)
          keys = ScopeIds(None, aside_type, aside_def_id, aside_usage_id)
          aside = aside_class.parse_xml(node, self, keys, id_generator)
          aside.save()
docs: Create an aside from the xml and attach it to the given block