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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 _send_ffs(self, pid, n_blocks, fr):
 """Send a flood-fill start packet. The cores and regions that the application should be loaded to will be specified by a stream of flood-fill core select packets (FFCS). """

        sfr = fr | (1 << 31)
        self._send_scp(
            255, 255, 0, SCPCommands.nearest_neighbour_packet,
            (NNCommands.flood_fill_start << 24) | (pid << 16) |
            (n_blocks << 8), 0x0, sfr
        )