code: def protoc_command(lang, output_dir, proto_path, refactored_dir):
      
      proto_files = glob.glob(os.path.join(refactored_dir, '*.proto'))
      cmd = ['protoc', '-I', proto_path, '--{}_out'.format(lang), output_dir]
      cmd.extend(proto_files)
      print(' '.join(cmd))
      p = subprocess.Popen(
          cmd, stdout=sys.stdout, stderr=sys.stderr, stdin=sys.stdin,
          cwd=proto_path)
      p.communicate()
docs: Runs the "protoc" command on the refactored Protobuf files to generate
      the source python/python3 files.
  
      Args:
          lang (str): the language to compile with "protoc"
                      (i.e. python, python3)
          output_dir (str): the output directory for the generated source files
          proto_path (str): the root protobuf build path in which to run "protoc"
          refactored_dir (str): the input directory of the Protobuf files