'Marshmallow' object has no attribute 'ModelSchema'

Conf.py

from flask_sqlalchemy import SQLAlchemy
from flask_marshmallow import Marshmallow

db = SQLAlchemy(app)
ma = Marshmallow(app) 

# flask-marshmallow<0.12.0

class UserSchema(ma.ModelSchema):
      class Meta:
            model = User

# flask-marshmallow>=0.12.0 (recommended)

from conf import ma
class UserSchema(ma.SQLAlchemyAutoSchema):
      class Meta:
            model = User
            load_instance = True

# flask-marshmallow>=0.12.0 (not recommended)

from marshmallow_sqlalchemy import ModelSchema
class UserSchema(ModelSchema):
      class Meta:
            model = User
            sql_session = db.session

I hate when it happens, but i got the answer immediately after posting...

Was installed only flask-marshmallow, but

pipenv install marshmallow-sqlalchemy

needed to add to work with SQLAlchemy. Whole code stays the same.

Maybe it will help someone... Now i got a different issue but that's another story.