create table issue use sqlalchemy-clickhouse

engine = create_engine('clickhouse://default:@localhost/test',encoding='utf-8',echo=True)
Base = declarative_base()
class Users(Base):
**tablename** = 'users'
id = Column(Integer,primary_key=True)
name = Column(String(32))
password = Column(String(64))
engine = Engine()
Base.metadata.create_all(engine)
traceback like this:
Exception: Code: 62, e.displayText() = DB::Exception: Syntax error: failed at position 45 (line 3, col 13): NOT NULL,
name VARCHAR(32),
password VARCHAR(64),
PRIMARY KEY (id)

I want create table use python code like this, but can't create it ,so what could i do to create it.
thanks