@type t() :: %Reactor.Process.Dsl.StartChild{
  __identifier__: any(),
  arguments: [Reactor.Dsl.Argument.t()],
  child_spec: Reactor.Process.Dsl.ChildSpec.t(),
  description: nil | String.t(),
  fail_on_already_present?: boolean(),
  fail_on_already_started?: boolean(),
  guards: [Reactor.Guard.Build.t()],
  module: module(),
  name: any(),
  supervisor: Reactor.Template.t() | Supervisor.supervisor(),
  terminate_on_undo?: boolean(),
  termination_reason: any(),
  termination_timeout: timeout()
}