hats = ["red", "black", "blue", "yellow"]
ids = [2, 7, 15, 22, 25, 34]

newIds = [] # Initialize a new list so we can add to it in a loop
for id in ids:
    if id % 2 == 0: # is the number even? (is the remainder 0 after division by 2?)
        newIds.append(id + 1)
    elif id % 2 == 1: # is the number odd? (remainder == 1 after division by 2?)
        newIds.append(id - 1)

# len(hats) → length of the "hats" list; range(len(hats)) list containing [0, 1, 2, … n], where n is the length of the list minus 1 (the last index of "hats")
for i in range(len(hats)):
    print "person with id", newIds[i], "has a", hats[i], "hat"