src/Shared/Delegator/DelegatorTrait.php
protected function getFromLookup(/*# string */ $key)
    {
        // found already ? or try find
        if ($key === $this->cache_key || $this->hasInLookup($key)) {
            return $this->getFromRegistry($this->cache_reg, $key);
        }
        // not found
        return null;
    }
protected function getFromLookup(/*# string */ $key)
    {
        // found already ? or try find
        if ($key === $this->cache_key || $this->hasInLookup($key)) {
            return $this->getFromRegistry($this->cache_reg, $key);
        }
        // not found
        return null;
    }
get from lookup pool, return NULL if not found

@param  string $key
@return mixed|null
@access protected