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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 read(self, size=None):
 """Read at most size bytes from this buffer. Bytes read from this buffer are consumed and are permanently removed. Args: size: If provided, read no more than size bytes from the buffer. Otherwise, this reads the entire buffer. Returns: The bytes read from this buffer. """

        if size is None:
            size = self.__size
        ret_list = []
        while size > 0 and self.__buf:
            data = self.__buf.popleft()
            size -= len(data)
            ret_list.append(data)
        if size < 0:
            ret_list[-1], remainder = ret_list[-1][:size], ret_list[-1][size:]
            self.__buf.appendleft(remainder)
        ret = b''.join(ret_list)
        self.__size -= len(ret)
        return ret