Elif

elif chains extra conditions between if and else. Python checks each condition from the top and runs the block of the first one that is True:

def ticket_price(age):
    if age < 6:
        return 0
    elif age < 18:
        return 50
    else:
        return 100

print(ticket_price(3))
print(ticket_price(12))
print(ticket_price(40))

Output:

0
50
100

Order matters. For age = 3, both age < 6 and age < 18 are True, but only the first matching block runs. That is why age < 18 does not need to say "and at least 6" — earlier conditions already handled everything below 6.

A chain can have any number of elif blocks. The else at the end is optional; without it, a value that matches nothing falls through and no block runs.

Exercise

1. Define a function named shipping_zone with one parameter, weight (kilograms).
2. Return a string by these rules, checked in order:
3. under 1: "letter"
4. under 10: "parcel"
5. under 30: "freight"
6. anything else: "pallet"

shipping_zone(0.4) returns "letter". shipping_zone(10) returns "freight".

Run your code to see the output, then press Submit.

Tests

import unittest


class TestShippingZone(unittest.TestCase):
    def test_under_1_kg_is_a_letter(self):
        self.assertEqual(shipping_zone(0.4), "letter")

    def test_5_kg_is_a_parcel(self):
        self.assertEqual(shipping_zone(5), "parcel")

    def test_exactly_1_kg_is_a_parcel(self):
        self.assertEqual(shipping_zone(1), "parcel")

    def test_exactly_10_kg_is_freight(self):
        self.assertEqual(shipping_zone(10), "freight")

    def test_75_kg_is_a_pallet(self):
        self.assertEqual(shipping_zone(75), "pallet")