src/fn/Map/Tree.php
private function validateInner(Iterator $inner): bool
    {
        if (!($this->currentValid = $inner->valid())) {
            $this->currentKey = null;
            $this->currentValue = null;
            $this->children = null;
        }
        return $this->currentValid;
    }
private function validateInner(Iterator $inner): bool
    {
        if (!($this->currentValid = $inner->valid())) {
            $this->currentKey = null;
            $this->currentValue = null;
            $this->children = null;
        }
        return $this->currentValid;
    }
@param Iterator $inner

@return bool