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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 get_batch_method(self):
 """ Returns a change batch for SharePoint's UpdateListItems operation. """

        if not self._changed:
            return None

        batch_method = E.Method(Cmd='Update' if self.id else 'New')
        batch_method.append(E.Field(text_type(self.id) if self.id else 'New',
                                    Name='ID'))
        for field in self.fields.values():
            if field.name in self._changed:
                value = field.unparse(self._data[field.name] or '')
                batch_method.append(E.Field(value, Name=field.name))
        return batch_method