为什么下面的Couchbase async Python代码不能工作？

from couchbase.cluster import Cluster
from couchbase.cluster import PasswordAuthenticator
from couchbase.n1ql import N1QLQuery

cluster = Cluster('couchbase://localhost')
authenticator = PasswordAuthenticator('username', 'password')
cluster.authenticate(authenticator)
bucket = cluster.open_bucket('bucket_name')

query = N1QLQuery('SELECT * FROM bucket_name WHERE field = "value"')
result = bucket.n1ql_query(query)

for row in result:
    print(row)