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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 to_numpy_(self, table_name: str="data") -> numpy.array: """Convert the main dataframe to a numpy array :param table_name: name of the python variable, defaults to "data" :param table_name: str, optional :return: a numpy array :rtype: np.array :example: ``ds.to_numpy_("myvar")`` """

        try:
            renderer = pytablewriter.NumpyTableWriter
            data = self._build_export(renderer, table_name)
            return data
        except Exception as e:
            self.err(e, "Can not convert data to numpy array")