code: def plot_histogram(self, title_prefix="", title_override="",
                         figsize=(8, 6)):
          
          # Check that roll_mc has been called
          if not self.arr_res:
              raise ValueError("Call roll_mc before plotting the histogram.")
          # Find a title using either the override or _construct_title method
          if title_override:
              title = title_override
          else:
              title = title_prefix + PBE._construct_title(self.num_dice,
                  self.dice_type, self.add_val, self.num_attribute,
                  self.keep_attribute, self.keep_dice, self.reroll,
                  self.num_arrays)
          # Construct the histogram
          f = self._plot_hist(self.arr_res, self.pbe_res, title, figsize)
          return f
docs: Plots a histogram of the results after the Monte Carlo simulation is
          run. NOTE- This method must be called AFTER "roll_mc".
  
          :param title_prefix: If desired, prefix the title (such as "Alg 1")
          :param title_override: Override the title string entirely
          :param figsize: The size of the histogram plot
          :return: a seaborn figure of the histogram