Convenience function to retrieve just the "page" part of the input. This corresponds to what might be called the "path" component of a URL, except that we're using URLs with hashes before the path & query (e.g.: http://www.example.com/#!/virtual/path?and=params)
get_page(session = shiny::getDefaultReactiveDomain())
The current Shiny Session
The current page in a length-1 character vector, or FALSE if the input has no value.