Create a Full Text Search index with SQLAlchemy on PostgreSQL

I need to create a PostgreSQL Full Text Search index in Python with SQLAlchemy. Here's what I want in SQL:

CREATE TABLE person ( id INTEGER PRIMARY KEY, name TEXT );
CREATE INDEX person_idx ON person USING GIN (to_tsvector('simple', name));

Now how do I do the second part with SQLAlchemy when using the ORM:

class Person(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)

You could create index using Index in __table_args__. Also I use a function to create ts_vector to make it more tidy and reusable if more than one field is required. Something like below:

from sqlalchemy.dialects import postgresql
from sqlalchemy.sql import func

def create_tsvector(*args):
    exp = args[0]
    for e in args[1:]:
        exp += ' ' + e
    return func.to_tsvector('english', exp)

class Person(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String)

    __ts_vector__ = create_tsvector(
        cast(func.coalesce(name, ''), postgresql.TEXT)
    )

    __table_args__ = (
        Index(
            'idx_person_fts',
            __ts_vector__,
            postgresql_using='gin'
        )
    )

Update: A sample query using index (corrected based on comments):

people = Person.query.filter(Person.__ts_vector__.match(expressions, postgresql_regconfig='english')).all()