pub fn compose_conditional(
  name: String,
  condition: fn(types.FlowInstance) -> String,
  flows: dict.Dict(
    String,
    types.Flow(dynamic.Dynamic, session, error),
  ),
  storage: types.FlowStorage(error),
) -> types.Flow(types.ComposedStep, session, error)

pub fn compose_parallel(
  name: String,
  flows: List(types.Flow(dynamic.Dynamic, session, error)),
  merge_results: fn(List(dict.Dict(String, String))) -> dict.Dict(
    String,
    String,
  ),
  storage: types.FlowStorage(error),
) -> types.Flow(types.ComposedStep, session, error)

pub fn compose_sequential(
  name: String,
  flows: List(types.Flow(dynamic.Dynamic, session, error)),
  storage: types.FlowStorage(error),
) -> types.Flow(types.ComposedStep, session, error)

pub fn validation_middleware(
  validator: fn(types.FlowInstance) -> Result(Nil, String),
) -> fn(
  bot.Context(session, error),
  types.FlowInstance,
  fn() -> Result(
    #(
      bot.Context(session, error),
      types.FlowAction(step_type),
      types.FlowInstance,
    ),
    error,
  ),
) -> Result(
  #(
    bot.Context(session, error),
    types.FlowAction(step_type),
    types.FlowInstance,
  ),
  error,
)