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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 _get_progress_bar(self, progress_bar_type):
 """Construct a tqdm progress bar object, if tqdm is installed."""

        if tqdm is None:
            if progress_bar_type is not None:
                warnings.warn(_NO_TQDM_ERROR, UserWarning, stacklevel=3)
            return None

        description = "Downloading"
        unit = "rows"

        try:
            if progress_bar_type == "tqdm":
                return tqdm.tqdm(desc=description, total=self.total_rows, unit=unit)
            elif progress_bar_type == "tqdm_notebook":
                return tqdm.tqdm_notebook(
                    desc=description, total=self.total_rows, unit=unit
                )
            elif progress_bar_type == "tqdm_gui":
                return tqdm.tqdm_gui(desc=description, total=self.total_rows, unit=unit)
        except (KeyError, TypeError):
            # Protect ourselves from any tqdm errors. In case of
            # unexpected tqdm behavior, just fall back to showing
            # no progress bar.
            warnings.warn(_NO_TQDM_ERROR, UserWarning, stacklevel=3)
        return None