This gist shows how to determine if two line segments intersects.

DetermineCounterClockwise.py

#define a class to represent the x and y coordinates of points
class Point:
    def __init__(self,x,y):
        self.x = x
        self.y = y
        
#judges if point A,B,C are counter-clockwise
def ccw(A,B,C):
	return (C.y-A.y)*(B.x-A.x) > (B.y-A.y)*(C.x-A.x)

DetermineLineIntersect.py

#determining if line segments AB and CD intersects
def intersect(A,B,C,D):
	return ccw(A,C,D) != ccw(B,C,D) and ccw(A,B,C) != ccw(A,B,D)