def METHOD_NAME(var_dist, save_dir='dist_pdf'):
    """
    Draw histogram for distributtion of variables in that in var_dist.
    Args:
        var_dist(dict): numpy array of variables distribution.
        save_dir(str): dirname to save pdf. Default is 'dist_pdf'
    """
    numbers = len(var_dist)
    if save_dir is not None:
        if not os.path.exists(save_dir):
            os.mkdir(save_dir)
        pdf_path = os.path.join(save_dir, 'result.pdf')
        with PdfPages(pdf_path) as METHOD_NAME:
            for i, name in enumerate(var_dist.keys()):
                if i % 10 == 0:
                    _logger.info("plt {}/{}".format(i, numbers))
                arr = var_dist[name]
                arr = arr.flatten()
                weights = np.ones_like(arr) / len(arr)
                plt.hist(arr, bins=1000, weights=weights)
                plt.xlabel(name)
                plt.ylabel("frequency")
                plt.title("Hist of variable {}".format(name))
                plt.show()
                METHOD_NAME.savefig()
                plt.close()
    _logger.info(
        "variables histogram have been saved as {}".format(pdf_path))