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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def touch(self, mode=0o666, exist_ok=True):
 """Create a fake file for the path with the given access mode, if it doesn't exist. Args: mode: the file mode for the file if it does not exist exist_ok: if the file already exists and this is True, nothing happens, otherwise FileExistError is raised Raises: OSError: (Python 2 only) if the file exists and exits_ok is False. FileExistsError: (Python 3 only) if the file exists and exits_ok is False. """

        if self._closed:
            self._raise_closed()
        if self.exists():
            if exist_ok:
                self.filesystem.utime(self._path(), None)
            else:
                self.filesystem.raise_os_error(errno.EEXIST, self._path())
        else:
            fake_file = self.open('w')
            fake_file.close()
            self.chmod(mode)