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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 recv_file_from_remote(dev, src_filename, dst_file, filesize):
 """Intended to be passed to the `remote` function as the xfer_func argument. Matches up with send_file_to_host. """

    bytes_remaining = filesize
    if not HAS_BUFFER:
        bytes_remaining *= 2  # hexlify makes each byte into 2
    buf_size = BUFFER_SIZE
    write_buf = bytearray(buf_size)
    while bytes_remaining > 0:
        read_size = min(bytes_remaining, buf_size)
        buf_remaining = read_size
        buf_index = 0
        while buf_remaining > 0:
            read_buf = dev.read(buf_remaining)
            bytes_read = len(read_buf)
            if bytes_read:
                write_buf[buf_index:bytes_read] = read_buf[0:bytes_read]
                buf_index += bytes_read
                buf_remaining -= bytes_read
        if HAS_BUFFER:
            dst_file.write(write_buf[0:read_size])
        else:
            dst_file.write(binascii.unhexlify(write_buf[0:read_size]))
        # Send an ack to the remote as a form of flow control
        dev.write(b'\x06')   # ASCII ACK is 0x06
        bytes_remaining -= read_size