src/Lumper/Lumper.php
protected function _unique(callable $callback, $hash)
    {
        if (null === $hash || $hash instanceof Slice)
        {
            $hash .= $this->_string($callback);
        }

        return $hash;
    }
protected function _unique(callable $callback, $hash)
    {
        if (null === $hash || $hash instanceof Slice)
        {
            $hash .= $this->_string($callback);
        }

        return $hash;
    }
@param callable $callback
@param string   $hash

@return string