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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 _pad_data(self, max_len=None):
 """ Pad the data in DataFrame with [None} to ensure that all columns have the same length. :param max_len: If provided will extend all columns to this length, if not then will use the longest column :return: nothing """

        if not max_len:
            max_len = max([len(x) for x in self._data])
        for _, col in enumerate(self._data):
            col.extend([None] * (max_len - len(col)))