class_docstr: object for annotation documents
  
  Args:
      self.doc_text (str): document text
      self.annotation_set (list(str)): list of all annotations in doc
      self.spans (list(dict)): list of span dict, each span_dict is structured as follows:
          { 'end': (int), 'start': (int), 'type': (str) string of annotation }
docstr: Return json representations of the object
  
  Returns:
      :obj:`json`: json representations of the object
docstr_tok: ["Return","json","representations","of","the","object","Returns",":",":","obj",":","`","json","`",":","json","representations","of","the","object"]
code: def json(self):
      """
      Return json representations of the object
  
      Returns:
          :obj:`json`: json representations of the object
      """
      return json.dumps(self.__dict__)
  
imports: from __future__ import unicode_literals, print_function, division, absolute_import
  import json
label_desc: Use image node_id 2 for calling the HighLevelDoc obj's underlying member method code with example usage: obj.json() and returns: json