code: def raise_on_exist_ro_file(filename):
      try:
          file_stat = os.stat(
              filename
          )  # use stat to do exists + can write to check without race condition
      except OSError:
          return None  # swallow does not exist or other errors
  
      if (
          file_stat.st_mtime != 0
      ):  # if os.stat returns but modification is zero that's an invalid os.stat - ignore it
          if not (file_stat.st_mode & stat.S_IWUSR):
              raise PermissionError(
                  "Permission denied: {!r}".format(filename)
              )
  
imports: import os
  import stat
  import sys
label_desc: Use image node_id 1 for calling a global function with example usage: raise_on_exist_ro_file(filename) and returns: None