def plot_historical_relevance(self, word, period, method, smooth=None):
        time_series = TimeSeries(word)
        series = time_series.get_series()
        original_series = time_series.get_modified_series(series)
        if smooth != None:
            series = time_series.smoothify_series(original_series, smooth)
        else:
            series = original_series

        x0 = [i + self.year_range[0] for i in range(self.max_range)]
        y0 = self.compute_relevance(original_series)

        if 'level' in method:
            level_peak = LevelPeakDetector(series)
            if method == 'level 1':
                y = self.compute_relevance(level_peak.get_levels(1))
            else:
                y = self.compute_relevance(level_peak.get_levels(2))
        elif 'window' in method:
            window_peak = WindowPeakDetector(series)
            if method == 'window 1':
                y = self.compute_relevance(window_peak.compute_peaks(1))
            elif method == 'window 2':
                y = self.compute_relevance(window_peak.compute_peaks(2))
            else:
                y = self.compute_relevance(window_peak.compute_peaks(3))
        elif 'double' in method:
            double_peak = DoubleChangePeakDetector(series)
            y = double_peak.compute_relevance(0.1)

        plotter = Plotter(x0, series, period)
        plotter.plot_peaks(word, y, method + ' function')