Create and import your own module

Save a function in study_math.py and import it from a second file in the same directory. Create both files in your editor: study_math.py holds the function, and main.py imports and uses it. Run python main.py from that folder. A module executes its top-level statements once when first imported in a process.

Worked example

def total(values):
    return sum(values)

import study_math

print(study_math.total([20, 25]))

45

Why this works

The import searches the script directory and other entries on sys.path. Keeping definitions in a module lets multiple scripts reuse them.

Another case

def greet(name):
    return f"Hi, {name}"

import greetings

print(greetings.greet("Sam"))

Hi, Sam

Practice

Add an average(values) function to study_math.py and call it from main.py. Decide what should happen for an empty list.

Try another case

You save a script as random.py, and another script in the same folder runs import random. What goes wrong?