class_docstr: A single QA candidate answer.
code: def set_answer_string(self, token_offsets, document_text):
      (
          pred_str,
          self.offset_answer_start,
          self.offset_answer_end,
      ) = self._span_to_string(token_offsets, document_text)
      self.offset_unit = "char"
      self._add_answer(pred_str)
  
imports: from typing import List, Any
  from abc import ABC
  import logging
label_desc: Use image node_id 3 for calling the QACandidate obj's underlying member method code with example usage: obj.set_answer_string(token_offsets, document_text) without return types