Counter({(139713821424456): 5, (139713821196512): 5})
Counter({(139713821196512): 1, (139713821669136): 1, (139713821668776): 1,
    (139713821196584): 1, (139713821669064): 1, (139713821668560): 1, (
    139713821658792): 1, (139713821668704): 1, (139713821668848): 1, (
    139713821668632): 1})
With python csv module, why does creating a list of identical values speed up creation of a list of rows?