class_docstr: Adapt msg protocol v5 to v4
class_docstr_tok: ["Adapt","msg","protocol","v5","to","v4"]
code: def execute_request(self, msg):
      content = msg["content"]
      content.setdefault("user_variables", [])
      return msg
  
imports: import re
  import json
  from jupyter_client import protocol_version_info
label_desc: Use image node_id 3 for calling the V5toV4 obj's underlying member method code with example usage: obj.execute_request(msg) and returns: msg