Film director K. Balachander used Gopalnath's services in his Tamil film "Duet".

Entity and relation annotations:
id: 0
type: entity
value: text: K. Balachander
labels: <Person>
id: 1
type: entity
value: text: "Duet"
labels: <Work_of_art>
id: 2
type: entity
value: text: Gopalnath
labels: <Production>
id: 3
type: entity
value: text: Film director
labels: <Title>
type: relation
to_id: 1
labels: Person:creates:Work_of_art
from_id: 0
type: relation
to_id: 3
labels: Person:holds_title:Title
from_id: 0
type: relation
to_id: 2
labels: Person:owns/uses:Production
from_id: 0