WorkflowDefinition
    graph       (WorkflowGraph UserId FileId)
    scope       WorkflowInstanceScope'

WorkflowInstance
    definition  WorkflowDefinition
    graph       (WorkflowGraph UserId FileId)
    scope       (WorkflowInstaceScope TermId SchoolId CourseId)

Workflow
    instance    WorkflowInstance
    graph       (WorkflowGraph UserId FileId)
    initiator   UserId Maybe
    payload     (WorkflowPayload UserId FileId)
    currentNode WorkflowGraphNodeLabel Maybe