@type t() :: %Sendio.Contacts.Contact{
  created_at: DateTime.t() | nil,
  email: String.t() | nil,
  first_name: String.t() | nil,
  id: String.t(),
  last_name: String.t() | nil,
  properties: map() | nil,
  unsubscribed: boolean() | nil,
  updated_at: DateTime.t() | nil
}