docs: def get_color(self, color):
          '''
          Returns a color to use.
  
          :param integer/string color:
              Color for the plot. Can be an index for the color from COLORS
              or a key(string) from CNAMES.
          '''
          if color is None:
              color = self.counter
          if isinstance(color, str):
              color = CNAMES[color]
          self.counter = color + 1
          color %= len(COLORS)
          return color