code: def check_valid_color(color):
      
      if color in list(mcolors.CSS4_COLORS.keys()) + ["#4CB391"]:
          logging.info("Nanoplotter: Valid color {}.".format(color))
          return color
      else:
          logging.info("Nanoplotter: Invalid color {}, using default.".format(color))
          sys.stderr.write("Invalid color {}, using default.\n".format(color))
          return "#4CB391"
docs: Check if the color provided by the user is valid.
  
      If color is invalid the default is returned.