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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def check_valid_color(color):
 """Check if the color provided by the user is valid. If color is invalid the default is returned. """

    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"