Given a list of points that form a polygon when joined sequentially, find if this polygon is convex (Convex polygon definition).
- There are at least 3 and at most 10,000 points.
- Coordinates are in the range -10,000 to 10,000.
- You may assume the polygon formed by given points is always a simple polygon (Simple polygon definition). In other words, we ensure that exactly two edges intersect at each vertex, and that edges otherwise don't intersect each other.