Possible to configure a conditional must_exist validator?

[jtpavlock]

Is it possible to create a configuration validator that would require the presence of an option if another option is present?

For example, say I have the following config options:

• login_to_account
• username
• password

I'd like to require the username and password to be present only if login_to_account is true.

[rochacbruno]

Validator(
        "username",
        "password",
        must_exist=True,
        when=Validator(
            "login_to_account", must_exist=True,
        ),
    ),

[jtpavlock]

Thanks!