getVerticalLine function
Implementation
List<List<double>> getVerticalLine(List<List<double>> points) {
for (int i = 0, j = 1; j < points.length; i++, j++) {
final p1 = points[i], p2 = points[j];
if (p1[0] == p2[0]) return [p1, p2];
}
return [];
}