tasks:
  a:
    commands:
      - echo Begin a
      - unknown-cmd
      - echo End a
    on_failure: continue
  b:
    commands:
      - echo Begin b
      - unknown-cmd
      - echo End b
    depends_on: [ a ]
    on_failure: exit
  c:
    commands:
      - echo Begin c
      - sleep 1
      - echo End c
    depends_on: [ a ]
  d:
    commands:
      - echo Begin d
      - sleep 0.5
      - echo End d
    depends_on: [ a ]
  e:
    commands:
      - echo Begin e
      - sleep 0.5
      - echo End e
    depends_on: [ b, c, d ]
concurrency: 2