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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 truncate(hmac_result, length=6):
 """ Perform the truncating. """

    assert(len(hmac_result) == 20)
    offset   =  ord(hmac_result[19]) & 0xf
    bin_code = (ord(hmac_result[offset]) & 0x7f) << 24 \
        | (ord(hmac_result[offset+1]) & 0xff) << 16 \
        | (ord(hmac_result[offset+2]) & 0xff) <<  8 \
        | (ord(hmac_result[offset+3]) & 0xff)
    return bin_code % (10 ** length)