class_docstr: Mixin to create documents that conform to the load/save spec.
code: def load(self, uri):
      raise NotImplementedError("haven't written this yet")
  
imports: import copy
  import xml.dom
  from xml.dom.NodeFilter import NodeFilter
label_desc: Use image node_id 4 for calling the DocumentLS obj's underlying member method code with example usage: obj.load(uri) without return types