function herman() {
	int x1  := 0;
	int x2  := 0;
	int x3  := 0;
	int x4  := 0;
	int x5  := 0;
	int x6  := 0;
	int x7  := 0;
	int oldx1 := 0;
	int oldx2 := 0;
	int oldx3 := 0;
	int oldx4 := 0;
	int oldx5 := 0;
	int oldx6 := 0;
	int oldx7 := 0;

	{x1  := 0;} [] {x1 := 1;}
	{x2  := 0;} [] {x2 := 1;}
	{x3  := 0;} [] {x3 := 1;}
	{x4  := 0;} [] {x4 := 1;}
	{x5  := 0;} [] {x5 := 1;}
	{x6  := 0;} [] {x6 := 1;}
	{x7  := 0;} [] {x7 := 1;}

	// finds a ring configuration with exactly one token in the ring.
	while((x1 + x2 + x3 + x4 + x5 + x6 + x7) != 1) {
		oldx1  := x1;
		oldx2  := x2;
		oldx3  := x3;
		oldx4  := x4;
		oldx5  := x5;
		oldx6  := x6;
		oldx7  := x7;
		if(x1 = oldx7) {
			{x1 := 0;} [0.5] {x1 := 1;}
		} else {
			x1 := oldx7;
		}
		oldx7 := 0;
		if(x2 = oldx1) {
			{x2 := 0;} [0.5] {x2 := 1;}
		} else {
			x2 := oldx1;
		}
		oldx1 := 0;
		if(x3 = oldx2) {
			{x3 := 0;} [0.5] {x3 := 1;}
		} else {
			x3 := oldx2;
		}
		oldx2 := 0;
		if(x4 = oldx3) {
			{x4 := 0;} [0.5] {x4 := 1;}
		} else {
			x4 := oldx3;
		}
		oldx3 := 0;
		if(x5 = oldx4) {
			{x5 := 0;} [0.5] {x5 := 1;}
		} else {
			x5 := oldx4;
		}
		oldx4 := 0;
		if(x6 = oldx5) {
			{x6 := 0;} [0.5] {x6 := 1;}
		} else {
			x6 := oldx5;
		}
		oldx5 := 0;
		if(x7 = oldx6) {
			{x7 := 0;} [0.5] {x7 := 1;}
		} else {
			x7 := oldx6;
		}
		oldx6 := 0;
	}
}