concepts:
  - id: a
    title: Foundations
    description: Introductory foundations concept with broad scope.
    prerequisites: [c]
  - id: b
    title: Advanced Analysis
    description: Advanced analysis of results in a difficult domain.
    prerequisites: [a]
  - id: c
    title: Methods
    description: Methods and procedures for analysis in context.
    prerequisites: [b]
  - id: isolated
    title: Isolated Topic
    description: A topic disconnected from the rest of the graph.
    prerequisites: []
  - id: bottleneck
    title: Core Bottleneck
    description: Central concept required by many dependents in the pack.
    prerequisites: []
  - id: d1
    title: Dependent One
    description: Depends on a single core bottleneck concept.
    prerequisites: [bottleneck]
  - id: d2
    title: Dependent Two
    description: Depends on a single core bottleneck concept.
    prerequisites: [bottleneck]
  - id: d3
    title: Dependent Three
    description: Depends on a single core bottleneck concept.
    prerequisites: [bottleneck]