def touch(self, filepath):
        """Touches the specified file so that its modified time changes."""
        if self.is_ssh(filepath):
            self._check_ssh()
            remotepath = self._get_remote(filepath)
            stdin, stdout, stderr = self.ssh.exec_command("touch {}".format(remotepath))
            stdin.close()
        else:
            os.system("touch {}".format(filepath))
Touches the specified file so that its modified time changes.