code: def checker(f):
      global CHECKERS
      CHECKERS.append(f)
      return f
  
imports: import argparse
  import commonmark
  import nbformat
  import os
  import re
  import subprocess
  import sys
  import textwrap
  from pathlib import Path
label_desc: Use image node_id 17 for calling a global function with example usage: checker(f) and returns: f