Heng Samrin and Chea Sim is the first and second positions in the Politburo.

Entity and relation annotations:
id: 0
type: entity
value: text: the Politburo
labels: <Organization>
id: 1
type: entity
value: text: Heng Samrin
labels: <Person>
id: 2
type: entity
value: text: Chea Sim
labels: <Person>
type: relation
to_id: 0
labels: Person:belongs_to_NORP:Organization
from_id: 2
type: relation
to_id: 0
labels: Person:belongs_to_NORP:Organization
from_id: 1