아톰오류

D:\workspace\python_mooc\lab_1_windows\windows>atom arithmetic_function.py

'atom'은(는) 내부 또는 외부 명령, 실행할 수 있는 프로그램, 또는

배치 파일이 아닙니다.

아톰오류라서 첫번째과제부터 힘들어요 

뭐가 문제인걸까요?

D:\workspace\python_mooc\lab_1_windows\windows>python

Python 3.7.4 (default, Aug  9 2019, 18:34:13) [MSC v.1915 64 bit (AMD64)] :: Anaconda, Inc. on win32

Warning:

This Python interpreter is in a conda environment, but the environment has

not been activated.  Libraries may fail to load.  To activate this environment

please see https://conda.io/activation

Type "help", "copyright", "credits" or "license" for more information.

>>> import arithmetic_funcion

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

ModuleNotFoundError: No module named 'arithmetic_funcion'

>>> arithmetic_function.addition(5,8)

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

NameError: name 'arithmetic_function' is not defined

이런거만 자꾸 뜨는데 아예 모르겠어요 ㅠㅠ