How to update the environment variables in linux and access in python?

1. We need to open the environment file using command
   sudo nano /etc/environment
 
2. Update the variables in new line eg.
   ABC = "test"

3. Save the file using ctl+o

4. Reboot the system.

5. Then we can call the environment variable using this method.
import os
info = os.environ.get('ABC')
print(info)

Output will be - test