docs: def check_or_confirm_overwrite(file_name):
      """
      Returns True if OK to proceed, False otherwise
      """
      try:
          with open(file_name) as fd:
              header = next(fd)
              if header.find(':sedge:') == -1:
                  okay = ask_overwrite(file_name)
                  if okay:
                      backup_file(file_name)
                  else:
                      return False
  
      except FileNotFoundError:
          click.echo("{} not found".format(file_name), err=True)
      except StopIteration as e:
          click.echo(repr(e), err=True)
      else:
          return True