class_docstr: Mixin to create documents that conform to the load/save spec.
code: def _set_async(self, flag):
      if flag:
          raise xml.dom.NotSupportedErr(
              "asynchronous document loading is not supported"
          )
  
imports: import copy
  import xml.dom
  from xml.dom.NodeFilter import NodeFilter
label_desc: Use image node_id 2 for calling the DocumentLS obj's underlying member method code with example usage: obj._set_async(flag) without return types