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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 wwpn_alloc(self):
 """ Allocates a WWPN unique to this partition, in the range of 0xAFFEAFFE00008000 to 0xAFFEAFFE0000FFFF. Returns: string: The WWPN as 16 hexadecimal digits in upper case. Raises: ValueError: No more WWPNs available in that range. """

        wwpn_int = self._wwpn_pool.alloc()
        wwpn = "AFFEAFFE0000" + "{:04X}".format(wwpn_int)
        return wwpn