7 Control Flow

import sys
sys.version

'3.13.3 (main, Apr  8 2025, 13:54:08) [Clang 16.0.0 (clang-1600.0.26.6)]'

7.1 `if` - `elif` - `else`

a = 4

Conditionals do not require parentheses:

if a < 10:
    print("hello")

hello

But they work with them just the same:

if (a < 10):
    print("hey")

hey

x1 = 9

if x1 > 10:
    print("x1 is greater than 10")
elif 5 < x1 <= 10:        
    print("x1 is between 5 and 10")
else:
    print("x1 is not very big")

x1 is between 5 and 10

for i in range(4):
    print("Working on Feature " + str(i))

Working on Feature 0
Working on Feature 1
Working on Feature 2
Working on Feature 3

enumerate(iterable, start=0) outputs pairs of an index (starting at start) and an item from iterable

a = ['one', 'two', 'three', 'four']

for it in enumerate(a):
    print(it)

(0, 'one')
(1, 'two')
(2, 'three')
(3, 'four')

for i, el in enumerate(a, start=1):
    print("Item number ", i, ": ", el, sep = '')

Item number 1: one
Item number 2: two
Item number 3: three
Item number 4: four

x = 18
while x > 12:
    x -= 1
    print(x)