polygons = [
[[1,7], [1,3], [2,3], [2,7]], # polygon 1
[[1,1], [1,5], [3,3]], # polygon 2
[[0,0], [0,5], [2,10], [4,7], [3,10], [8,2]] # polygon 3
]

for polygon in polygons:
    if len(polygon) < 3:
        print "This is not a polygon!"
    elif len(polygon) == 3:
        print "This is a triangle"
    elif len(polygon) == 4:
        print "This has four sides (might be a square?)."
    else:
        print "This is a more complex polygon."