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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 pack_remb_fci(bitrate, ssrcs):
 """ Pack the FCI for a Receiver Estimated Maximum Bitrate report. https://tools.ietf.org/html/draft-alvestrand-rmcat-remb-03 """

    data = b'REMB'
    exponent = 0
    mantissa = bitrate
    while mantissa > 0x3ffff:
        mantissa >>= 1
        exponent += 1
    data += pack('!BBH',
                 len(ssrcs),
                 (exponent << 2) | (mantissa >> 16),
                 (mantissa & 0xffff))
    for ssrc in ssrcs:
        data += pack('!L', ssrc)
    return data