module AbstractController::Caching::Fragments

def fragment_exist?(key, options = nil)

`expire_fragment` for acceptable formats).
Check if a cached fragment from the location signified by `key` exists (see 
def fragment_exist?(key, options = nil)
  return unless cache_configured?
  key = combined_fragment_cache_key(key)
  instrument_fragment_cache :exist_fragment?, key do
    cache_store.exist?(key, options)
  end
end