original_string: protected function ensureValidKeys($keys)
      {
          if (!is_array($keys) && !($keys instanceof \Traversable)) {
              throw new InvalidArgumentException('A cache key set must be either an array or a Traversable.');
          }
  
          foreach ($keys as $key) {
              $this->ensureValidKey($key);
          }
      }
code: protected function ensureValidKeys($keys)
      {
          if (!is_array($keys) && !($keys instanceof \Traversable)) {
              throw new InvalidArgumentException('A cache key set must be either an array or a Traversable.');
          }
  
          foreach ($keys as $key) {
              $this->ensureValidKey($key);
          }
      }
code_tokens: protected function ensureValidKeys ( $ keys ) { if ( ! is_array ( $ keys ) && ! ( $ keys instanceof \ Traversable ) ) { throw new InvalidArgumentException ( 'A cache key set must be either an array or a Traversable.' ) ; } foreach ( $ keys as $ key ) { $ this -> ensureValidKey ( $ key ) ; } }
docstring: Ensure the validity of the given cache keys.
  
  @param mixed $keys The keys to check.
  @return void
  @throws \Cake\Cache\InvalidArgumentException When the keys are not valid.
docstring_tokens: Ensure the validity of the given cache keys .