code: def to_dataframe(self, bqstorage_client=None, dtypes=None, progress_bar_type=None):
          
          if pandas is None:
              raise ValueError(_NO_PANDAS_ERROR)
          return pandas.DataFrame()
docs: 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`.