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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 DeriveReportKey(cls, root_key, report_id, sent_timestamp):
 """Derive a standard one time use report signing key. The standard method is HMAC-SHA256(root_key, MAGIC_NUMBER || report_id || sent_timestamp) where MAGIC_NUMBER is 0x00000002 and all integers are in little endian. """


        signed_data = struct.pack("<LLL", AuthProvider.ReportKeyMagic, report_id, sent_timestamp)

        hmac_calc = hmac.new(root_key, signed_data, hashlib.sha256)
        return bytearray(hmac_calc.digest())