A module is just a set of functions.

def add(a, b):
    return a + b

A user made module is loaded exactly the same way as the built-in module. The functions defined in the module are used as if they were methods.

from __future__ import print_function
import my_calculator

print(my_calculator.add(2, 3))  # 5
from __future__ import print_function
from my_calculator import add

print(add(2, 3))  # 5

We can import specific functions to the current name space (symbol table).