def zpartner(self):
"""
Property that returns the Z-partner of the given object if it exists,
otherwise returns None.
"""
if self._mod == 12:
zint = Z_PARTNERS.get(self.pcint, None)
if zint:
return self.copy(utils.fromint(zint))
else:
return
for each in self.each_card():
if each.icv == self.icv:
if each.prime._unique_pcs != self.prime._unique_pcs:
return self.copy(each)
