Doubt: How to specify collation on Documents(Collection)?

I have the following class:

class Subject(me.Document):
    name = me.StringField(unique=True)
    topic = me.StringField(required=True, choices=('Language', 'Other'))
    isCompulsory = me.BooleanField(required=True, default=False)

    meta = {
        'collation': {
            'locale': 'en',
            'caseLevel': False
        }
    }

The Docs do not provide any example.
I have two problems:

1. How can I make choices to be case-insensitive.
2. I am able to insert values like physics, Physics in name field. How to make DB treat them as same?

NB: I have dropped Collection (using MongoDB Compass) before trying this.
Info:

• MongoDB Version : 4.0.3

The issue names no repository file, test, or entry point; start by locating the documentation for Document/Collection collation and StringField choices, then verify the MongoDB 4.0.3 behavior described. Done means the documentation explains case-insensitive choices and duplicate handling for name, with an example covering the stated meta configuration.