src/AssignUUID.php
protected function assignUUID($field = null)
    {
        if ($field != null) {
            $this->{$field} = UUID::generate();
        } else {
            $this->id = UUID::generate();
        }
    }
protected function assignUUID($field = null)
    {
        if ($field != null) {
            $this->{$field} = UUID::generate();
        } else {
            $this->id = UUID::generate();
        }
    }
assignUUID

@param null $field