src/Shared/Delegator/DelegatorTrait.php
protected function hasInLookup(/*# string */ $key)/*# : bool */
    {
        foreach ($this->lookup_pool as $registry) {
            if ($this->hasInRegistry($registry, $key)) {
                $this->cache_key = $key;
                $this->cache_reg = $registry;
                return true;
            }
        }
        return false;
    }
protected function hasInLookup(/*# string */ $key)/*# : bool */
    {
        foreach ($this->lookup_pool as $registry) {
            if ($this->hasInRegistry($registry, $key)) {
                $this->cache_key = $key;
                $this->cache_reg = $registry;
                return true;
            }
        }
        return false;
    }
check existence in the whole lookup pool

@param  string $key
@return bool
@access protected