with_snapmail.ex

defmodule EvercamMedia.SnapmailController do
  ...
  def update(conn, %{"id" => snapmail_exid} = params) do
      current_user = conn.assigns[:current_user]

      with :ok <- authorized(conn, current_user),
           {:ok, cameras} <- ensure_cameras_exist("update", conn, params["camera_exids"], current_user),
           {:ok, snapmail} <- snapmail_exist(conn, snapmail_exid),
           true <- snapmail.user_id == current_user.id
      do
        # Code truncated for clarity...updates the Snapmail and associated worker
      else
        false -> render_error(conn, 401, "Unauthorized.")
      end
  end