<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def check_my_users(user):
 """Check if user exists and its credentials. Take a look at encrypt_app.py and encrypt_cli.py to see how to encrypt passwords """

    user_data = my_users.get(user['username'])
    if not user_data:
        return False  # <--- invalid credentials
    elif user_data.get('password') == user['password']:
        return True  # <--- user is logged in!

    return False