class Lookup

Makes a new lookup object, which contains information about the passed-in

locales. At present, if any one of the locales is not present verbatim,

an error is returned.

Errors:

- UNAVAILABLE: one of the requested locale IDs is not avalable for use.

- ARGUMENT_ERROR: the locales ids are malfomed, e.g. nonexistent, or

not a valid UTF8 encoding of the locale ID.

Looks up the message by its unique `message_id`.

Errors:

- UNAVAILABLE: the requested message ID is not present in the loaded

resource bundle.

Instantiates a fake Lookup instance, which is useful for tests that don't

want to make a full end-to-end localization setup.

The fake is simplistic and it is the intention that it provides you with

some default fake behaviors. The behaviors are as follows at the moment,

and more could be added if needed.

- If `locale_ids` contains the string `en-US`, the constructor will

return UNAVAILABLE.

- If the message ID pased to `Lookup::String()` is exactly 1, the fake

returns `Hello, {person}!`, so that you can test 1-parameter formatting.

- Otherwise, for an even mesage ID it returns "Hello world!", or for

an odd message ID returns UNAVAILABLE.

The implementation of the fake itself is done in rust behind a FFI ABI,

see the package //src/lib/intl/lookup/rust for details.

Same as above, except allows you to pass in custom behavior operations

for the fake and affect its behavior. As a user of this library you should

normally never need to use this particular constructor. If you need

special behavior, consider filing a feature request instead to component

"I18N>Localization" at https://fxbug.dev.

Error codes reported by New() and Lookup() methods.