Reader which uses python eval on each part of a tab separated string.
        Yields a tuple of python objects.

def internal_reader(self, input_stream):
        """
        Reader which uses python eval on each part of a tab separated string.
        Yields a tuple of python objects.
        """
        for input_line in input_stream:
            yield list(map(self.deserialize, input_line.split("\t")))