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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 gen_slot_variables(self, cls: ClassDefinition) -> str: """ Generate python definition for class cls, generating primary keys first followed by the rest of the slots """

        return '\n\t'.join([self.gen_slot_variable(cls, pk) for pk in self.primary_keys_for(cls)] +
                           [self.gen_slot_variable(cls, slot)
                            for slot in cls.slots
                            if not self.schema.slots[slot].primary_key and not self.schema.slots[slot].identifier])