# Tuple can be used as keys in mappings-lists can't be.
# Tuple are returned by some built-in functions and methods.
# The tuple syntax is simple-if you separate some values with commas, you automatically have a tuple:
x = 1, 2, 3
print x
# Tuples may also be enclosed in parentheses:
x = (1, 2, 3)
print x
# The empty tuple is written as two parentheses containing nothing:
x = ()
print x