Sample module / application

sample_app.py

#! /usr/bin/env python3

# -*- coding: utf-8 -*-
# encoding: utf-8
# coding: utf-8

"""
Sample cli application
"""

from __future__ import absolute_import, print_function, unicode_literals

import sys, os
from sample_module import CONSTANT, DATA, Antwort  # use sample module

question = "The Ultimate Question of Life, The Universe, and Everything"
print("My question is [{}].".format(question))

# use computation from sample module:
answer = Antwort(question) #!

print("Answer to my question is [{}].".format(answer))

sample_module.py

#! /usr/bin/env python3

# -*- coding: utf-8 -*-
# encoding: utf-8
# coding: utf-8

"""
Sample module, which can also be executed via command line
"""

from __future__ import absolute_import, print_function, unicode_literals

import sys, os

#################################################################
# Some global constant
CONSTANT = '42'

# Global data
DATA = os.environ.get('DATA', CONSTANT)

#################################################################
# Some general function
def Antwort(q):
    return(DATA)

#################################################################
# Note: this is the main trick to make this module separately usable:
if __name__ == "__main__": ## Execution via command line? 
    try:
        # user interaction:
        print('Input Your question: ?')
        question = input()
        answer = Antwort(question) # some computation
        print("Answer to your question [{}] is [{}].".format(question, answer))
        sys.exit(0)
    except KeyboardInterrupt:
        e = sys.exc_info()[1]
        sys.stderr.write("\nUser interrupted process.\n")
        sys.exit(0)
    except SystemExit:
        e = sys.exc_info()[1]
        sys.exit(e.code)
    except Exception:
        e = sys.exc_info()[1]
        sys.stderr.write("\nERROR: unhandled exception occurred: (%s).\n" % e)
        sys.exit(-1)
    finally:
        # some global cleanup
        print("So Long, and Thanks for All the Fish!")

Note: put both files into the same directory