voku / Stringy

     *

     * @return static <p>Object with all characters of $str being lowercase.</p>

     */

    public function toLowerCase($tryToKeepStringLength = false, $lang = null): self

    {

        return static::create(

            $this->utf8::strtolower(

                $this->str, $this->encoding, false, $lang, $tryToKeepStringLength

            ),

            $this->encoding

        );

    }

    /**

     * Converts each tab in the string to some number of spaces, as defined by

     *

     * @return static <p>Object with all characters of $str being uppercase.</p>

     */

    public function toUpperCase($tryToKeepStringLength = false, $lang = null): self

    {

        return static::create(

            $this->utf8::strtoupper($this->str, $this->encoding, false, $lang, $tryToKeepStringLength),

            $this->encoding

        );

    }

    /**

     * Returns a string with whitespace removed from the start and end of the