Helper to perform Assignment using Diffo.Provider.AssignmentRelationship.
Each assignment is stored as an AssignmentRelationship with top-level pool,
thing, and value attributes. This makes them filterable at the Cypher level
and usable in aggregate expressions.
Summary
Functions
Assign a thing using the pool declared via pools do on the instance module.
The thing name is looked up from the pool declaration.
Assign a thing using the instance changeset assignment.