def _get_free_field_name(self, field):
        num = 0
        field_name = unicode(field.name) + u"___" + unicode(num)
        while field_name in self.fields:
            num += 1
            field_name = unicode(field.name) + u"___" + unicode(num)
        return field_name
Generate an available name for a field
dataset/ETHPy150Open treeio/treeio/treeio/infrastructure/forms.py/ItemForm._get_free_field_name