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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 unread_data(self, data: bytes) -> None: """ rollback reading some data from stream, inserting it to buffer head. """

        warnings.warn("unread_data() is deprecated "
                      "and will be removed in future releases (#3260)",
                      DeprecationWarning,
                      stacklevel=2)
        if not data:
            return

        if self._buffer_offset:
            self._buffer[0] = self._buffer[0][self._buffer_offset:]
            self._buffer_offset = 0
        self._size += len(data)
        self._cursor -= len(data)
        self._buffer.appendleft(data)
        self._eof_counter = 0