def isConvex(self, points):

"""

def det(A):

return A[0][0]*A[1][1] - A[0][1]*A[1][0]

n, prev, curr = len(points), 0, None

for i in xrange(len(points)):

A = [[points[(i+j) % n][0] - points[i][0], points[(i+j) % n][1] - points[i][1]] for j in (1, 2)]

curr = det(A)

if curr:

if curr * prev < 0:

return False

prev = curr