def xread(
        self,
        streams: Dict[KeyT, StreamIdT],
        count: Optional[int] = None,
        block: Optional[int] = None,
    ) -> Awaitable:
        """
        Block and monitor multiple streams for new data.
        streams: a dict of stream names to stream IDs, where
                   IDs indicate the last ID already seen.
        count: if set, only return this many items, beginning with the
               earliest available.
        block: number of milliseconds to wait, if nothing already present.
        """
        pieces: List[EncodableT] = []
        if block is not None:
            if not isinstance(block, int) or block < 0:
                raise DataError("XREAD block must be a non-negative integer")
            pieces.append(b"BLOCK")
            pieces.append(str(block))
        if count is not None:
            if not isinstance(count, int) or count < 1:
                raise DataError("XREAD count must be a positive integer")
            pieces.append(b"COUNT")
            pieces.append(str(count))
        if not isinstance(streams, dict) or len(streams) == 0:
            raise DataError("XREAD streams must be a non empty dict")
        pieces.append(b"STREAMS")
        keys, values = zip(*streams.items())
        pieces.extend(keys)
        pieces.extend(values)
        return self.execute_command("XREAD", *pieces)

        Block and monitor multiple streams for new data.
        streams: a dict of stream names to stream IDs, where
                   IDs indicate the last ID already seen.
        count: if set, only return this many items, beginning with the
               earliest available.
        block: number of milliseconds to wait, if nothing already present.
        
aioredis/client.py