/// This trait is used to convert an enum into a string that can be used as a
/// Fluent choice.
///
/// # Example
///
/// ```rs
/// use es_fluent::EsFluentChoice;
///
/// enum MyEnum {
/// Variant1,
/// Variant2,
/// }
///
/// impl EsFluentChoice for MyEnum {
/// fn as_fluent_choice(&self) -> &'static str {
/// match self {
/// MyEnum::Variant1 => "variant1",
/// MyEnum::Variant2 => "variant2",
/// }
/// }
/// }
///
/// let my_enum = MyEnum::Variant1;
/// assert_eq!(my_enum.as_fluent_choice(), "variant1");
/// ```