How to get number length?

I want to set placeholder for numbel like "xxx-xxx-xx-xx", or if choosed different country different placeholder like for example "xx-xx-xxx". How i can get number length? Thank you!

The issue names no files or tests. Start by reviewing the library's phone-formatting and validation entry points, then determine how country-specific number lengths and placeholders should be represented; done requires an agreed behavior for the requested country-dependent placeholders.

Written by the indexing model from the issue text.