flow-1.0.0-beta8/modules/flow_context/flow_context.services.yml

services:
  context_stack.flow:
    class: Drupal\context_stack\ContextStack
    factory: ['@context_stack.factory', createStack]
    arguments: [flow]
    tags:
      - { name: context_stack }
  flow_context.flow_subscriber:
    class: Drupal\flow_context\EventSubscriber\FlowContextSubscriber
    arguments: ['@context_stack.flow']
    tags:
      - { name: event_subscriber }