s = {1, 2, 3}
t = frozenset([4, 5, 6])
u = s | t
print(u)

t = "ABC"
#u = s | t       # TypeError: unsupported operand type(s) for |: 'set' and 'str'

u = s.union(t)
print(u)

# copy()
print()
s = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
print(s)
m = s.copy()
print(m)
print(m is s)
print(m == s)