#You need Cluster instance's attribute named pixels:
def printCluster(cl):
print("---------------")
print("(" + str(cl.meanColor.r) + "," + str(cl.meanColor.g) + "," + str(cl.meanColor.b) + ")")
print("I have " + str(len(pixels)) + " pixels.")
for px in cl.pixels:
print("(" + str(px.point.x) + "," + str(px.point.y) + ") (" + str(px.color.r) + "," + str(px.color.g) + "," + str(px.color.b) + ")")