int index = 4;
string colourFormat = "[color={0}]{1}[/color]";

public Program()
{
	Runtime.UpdateFrequency = UpdateFrequency.Update1;
}

public void Main(string arg)
{
	switch (arg)
	{
		case "down":
			index++;
			break;
		case "up":
			index--;
			break;
	}


	Echo("// Colour Test");

	Echo(string.Format(colourFormat, "#ff00ff00", "---- Base line ----"));

	const int LINE_COUNT = 40;

	for (int i = 0; i < LINE_COUNT; i++)
	{
		string baseMsg = $"- Test line {i}";

		if (i == index)
		{
			Echo(string.Format(colourFormat, "#ffff0000", baseMsg));
		}
		else
		{
			Echo(baseMsg);
		}
	}
}