Function line_segment_vs_line_segment 

pub fn line_segment_vs_line_segment<T: Float + SignedNumberOps<T> + FloatOps<T>>(
    l1: Vec3<T>,
    l2: Vec3<T>,
    s1: Vec3<T>,
    s2: Vec3<T>,
) -> Option<Vec3<T>>

returns the intersection point if the line segment l1-l2 intersects with s1-s2