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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_dataframe(self, bqstorage_client=None, dtypes=None, progress_bar_type=None):
 """Create an empty dataframe. Args: bqstorage_client (Any):
 Ignored. Added for compatibility with RowIterator. dtypes (Any):
 Ignored. Added for compatibility with RowIterator. progress_bar_type (Any):
 Ignored. Added for compatibility with RowIterator. Returns: pandas.DataFrame: An empty :class:`~pandas.DataFrame`. """

        if pandas is None:
            raise ValueError(_NO_PANDAS_ERROR)
        return pandas.DataFrame()