@classmethod
def truecolor(cls, offset, r, g, b, brighten):
    """Convert RGB to ANSI true-color"""
    if brighten is not None:
        r, g, b = cls.enhanced(r, g, b, 1.25 if brighten else 0.8)
    return '%s;2;%s;%s;%s' % (8 + offset, r, g, b)
