src/Leevel/Collection/Collection.php
public function offsetUnset($index): void
    {
        if (isset($this->elements[$index])) {
            unset($this->elements[$index]);
        }
    }
public function offsetUnset($index): void
    {
        if (isset($this->elements[$index])) {
            unset($this->elements[$index]);
        }
    }
实现 ArrayAccess::offsetUnset.

@param mixed $index