Returns list of vcf_records. One per variant
        in the ALT column. Does not change INFO/FORMAT etc columns, which
        means that they are now broken

def to_record_per_alt(self):
        '''Returns list of vcf_records. One per variant
        in the ALT column. Does not change INFO/FORMAT etc columns, which
        means that they are now broken'''
        record_list = []
        for alt in self.ALT:
            record_list.append(copy.copy(self))
            record_list[-1].ALT = [alt]
        return record_list