colors = {'black', 'grey', 'red', 'blue', 'green'}
print(colors)

for i in colors:
    print(i)

colors.add('white')
print(colors)

colors.discard('grey')
print(colors)

print("=====================Math & Sets =========")
colors1 = {'black', 'grey', 'red'}
colors2 = {'black', 'blue'}

print("colors1: ", colors1)
print("colors2: ",colors2)
print("==============================")
print("Intersect: ", colors1 & colors2)
print("Union: ", colors1 | colors2)
print("Difference: ", colors1 - colors2)
print("Superset: ", colors1 > colors2)

items = set(("coffee", "tea", "black", "white"))