Confispex.init_once

You're seeing just the function init_once, go back to Confispex module for more information.
Link to this function

init_once(params, server \\ Confispex.Server)

Specs

init_once(
  %{
    :schema => module(),
    :context => context(),
    optional(:store) => store() | (() -> store())
  },
  GenServer.server()
) :: :ok

Initialize a state in server if it hasn't already been initialized