fix #170 - declare PhoneCode (and TelephoneNumber and Extension) using `export type XXX = string` instead of `export interface PhoneCode extends String { }`
fix #170 - declare PhoneCode (and TelephoneNumber and Extension) using `export type XXX = string` instead of `export interface PhoneCode extends String { }`

halt-hammerzeit/libphonenumber-js,halt-hammerzeit/libphonenumber-js