@type t() :: %Klaviyo.Opts{
  access_token: String.t(),
  api_key: String.t(),
  client: module(),
  client_opts: keyword(),
  headers: Klaviyo.HTTP.headers_t(),
  host: String.t(),
  json_codec: module(),
  path: String.t(),
  port: pos_integer(),
  protocol: String.t(),
  retry: boolean() | module(),
  retry_opts: keyword(),
  revision: String.t()
}