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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 _read_tempfile(self, filename):
        '''Read in and return file that's in the tempdir.

        :param filename: Name of the file to read.
        :type filename: str

        '''
        with open(os.path.join(self._tempdir, filename)) as f:
            return f.read()