code: def nan(self, s):
      # if s.strip() == "":
      # return self.NAN
      return s
  
file_path: DeepKE/example/llm/InstructKGC/kg2instruction/convert/converter/ner_converter.py
imports: import json
label_desc: Use image node_id 2 for calling the NERConverter obj's underlying member method code with example usage: obj.nan(s) and returns: s