Python Module

To import a Python module, you use the import statement.
import module_name

..
write your own, and use it in another program.  function to add/subtract two numbers in a file calculation.py. 

def add(x,y):

    return (x+y)

def sub(x,y):

    return (x-y) 

import calculation            #Importing calculation module

print(calculation.add(1,2))   #Calling function defined in add module. 

from calculation import add

print(add(1,2)) 

from calculation import add,sub 

 use of from .. import *:

from calculation import *

print(add(1,2))

print(sub(3,2))