code: def compile_tree():
      """Compile all Python files below current directory."""
      stat = os.system("python -m compileall .")
      if stat:
          msg = "*** ERROR: Some Python files in tree do NOT compile! ***\n"
          msg += "See messages above for the actual file that produced it.\n"
          raise SystemExit(msg)
  
imports: import os
  import sys
label_desc: Use image node_id 3 for calling a global function with example usage: compile_tree() without return types