code: def bounds(n = n_classes)
        raise ArgumentError, "n must be lesser than or equal to n_classes: #{n_classes}" if n > n_classes
  
        k = data.size
        bounds = []
  
        # the calculation of classes will never include the upper and
        # lower bounds, so we need to explicitly set them
        bounds[n] = data.last
        bounds[0] = 0
  
        for countNum in n.downto 2
          id = @lower_class_limits[k][countNum]
          bounds[countNum - 1] = data[id - 2]
          k = id - 1
        end
  
        bounds
      end
docs: get bounds array for `n` number of classes