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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_chunk(self, size=None):
 """ Reads lines from Xport file and returns as dataframe Parameters size : int, defaults to None Number of lines to read. If None, reads whole file. Returns ------- DataFrame """

        if size is None:
            size = self._chunksize
        return self.read(nrows=size)