def _watch_file(self, filepath, trigger_event=True):
is_new = filepath not in self._watched_files<EOL>if trigger_event:<EOL><INDENT>if is_new:<EOL><INDENT>self.trigger_created(filepath)<EOL><DEDENT>else:<EOL><INDENT>self.trigger_modified(filepath)<EOL><DEDENT><DEDENT>try:<EOL><INDENT>self._watched_files[filepath] = self._get_modified_time(filepath)<EOL><DEDENT>except OSError:<EOL><INDENT>return<EOL><DEDENT>
Adds the file's modified time into its internal watchlist.