Python3 Environment Variables Example using DOTENV Package
Populate Constants from Environment Variables Code 


# constants.py
import os
from cryptography.fernet import Fernet
from dotenv import load_dotenv

# Load environment variables from .env file
load_dotenv()

# Retrieve the decryption key and encrypted password from environment variables
DECRYPTION_KEY = bytes(os.getenv("DECRYPTION_KEY"), encoding='utf-8')
ENCRYPTED_PASSWORD = bytes(os.getenv("ENCRYPTED_PASSWORD"), encoding='utf-8')

# Create a cipher suite using the decryption key
cipher_suite = Fernet(DECRYPTION_KEY)

# Decrypt the password using the cipher suite and convert it to a string
password = cipher_suite.decrypt(ENCRYPTED_PASSWORD).decode()

# Print the decrypted password
print("Password: ", password)

.env Environment Variables File 

# .env
DECRYPTION_KEY="G5YLK1KdKpQZjT5p30Chd9SJ2KVc9e_7qeQ1EDufPHU="
ENCRYPTED_PASSWORD="gAAAAABkw6rzPNKDivFJgvBMkY_07i2MI0ZOmXMw-oJgTPXzLS8p7SmJ6O7uDiL652s8AjHc5kEoL6KX3Wy-gp4cSgfdsted3g=="

Example Output 

Decrypted password: Pa$$w0rd123!

Process finished with exit code 0