def lines_colinear(ab, cd):
<EOL>return point_on_line(ab, cd[<NUM_LIT:0>]) & point_on_line(ab, cd[<NUM_LIT:1>])<EOL>
liness_colinear((a, b), (c, d)) yields True if the lines containing points (a,b) and points (c,d)
are colinear and false otherwise. All of a, b, c, and d must be (x,y) coordinates or 2xN (x,y)
coordinate matrices, or (x,y,z) or 3xN matrices.