Slurp.ConnectionSupervisor.start_link

You're seeing just the function start_link, go back to Slurp.ConnectionSupervisor module for more information.
Link to this function

start_link(list)

Specs

start_link([{:id, blockchain_id()}]) ::
  Supervisor.on_start()
  | {:error, :blockchain_not_found | :rpc_endpoint_not_found}