python import environment variable not exist code example

Example 1: get environment variable python

import os

# Set environment variables
os.environ['API_USER'] = 'username'
os.environ['API_PASSWORD'] = 'secret'

# Get environment variables
USER = os.getenv('API_USER')
PASSWORD = os.environ.get('API_PASSWORD')

# Getting non-existent keys
FOO = os.getenv('FOO') # None
BAR = os.environ.get('BAR') # None
BAZ = os.environ['BAZ'] # KeyError: key does not exist.

Example 2: python check environment variable exists

from os import environ
if environ.get('Foo') is not None: