code: def add_color_to_scheme(scheme, name, foreground, background, palette_colors):
      
      if foreground is None and background is None:
          return scheme
  
      new_scheme = []
      for item in scheme:
          if item[0] == name:
              if foreground is None:
                  foreground = item[1]
              if background is None:
                  background = item[2]
              if palette_colors > 16:
                  new_scheme.append((name, '', '', '', foreground, background))
              else:
                  new_scheme.append((name, foreground, background))
          else:
              new_scheme.append(item)
      return new_scheme
docs: Add foreground and background colours to a color scheme