vo/Page.php
public function offsetSet($key, $value)
    {
        if (is_null($key)) {
            $this->content[] = $value;
        } else {
            $this->content[$key] = $value;
        }
    }
public function offsetSet($key, $value)
    {
        if (is_null($key)) {
            $this->content[] = $value;
        } else {
            $this->content[$key] = $value;
        }
    }
Set the item at the given offset.

@param  mixed $key
@param  mixed $value
@return void