class I18n::Config

def available_locales_set #:nodoc:

:nodoc:
that we can have faster lookups to do the available locales enforce check.
Caches the available locales list as both strings and symbols in a Set, so 
def available_locales_set #:nodoc:
  @@available_locales_set ||= available_locales.inject(Set.new) do |set, locale|
    set << locale.to_s << locale.to_sym
  end
end