script_11.py - Fibonacci Sequence Generator

Code

#!/usr/bin/env python3
"""Fibonacci sequence generator"""

n = int(input("How many Fibonacci numbers? "))

a, b = 0, 1

for _ in range(n):
    print(a)
    a, b = b, a + b

Explanation

Line 4: n = int(input("How many Fibonacci numbers? ")) - n stores how many numbers to generate

Line 6: a, b = 0, 1 - Tuple unpacking (multiple assignment in one line) - a gets value 0, b gets value 1 - Both variables assigned simultaneously - Comma creates a tuple: (0, 1) - Variables get corresponding tuple elements

Line 8: for _ in range(n): - _ is the loop variable (underscore) - Convention: use _ when you don't need the loop value - Just need to repeat n times, don't care about counter - _ is still a valid variable, just conventionally "ignored"

Line 10: a, b = b, a + b - Simultaneous assignment (tuple unpacking) - Right side evaluated first as tuple: (b, a+b) - Then both variables updated at once - Example: if a=0,b=1: (b, a+b) = (1, 0+1) = (1, 1), so a=1,b=1 - Then: if a=1,b=1: (b, a+b) = (1, 1+1) = (1, 2), so a=1,b=2 - Critical: both use old values for calculation, then both updated - Fibonacci pattern: each number is sum of previous two