lessElementsltlessElt0lessEltniflelengthlnlelengthtoListtnltniftruebltnliffalsetrueltntiffalsefalseltnlessEltsnlengthnil0lengthconsnlslengthltoListleafniltoListnodet1nt2appendtoListt1consntoListt2appendnill2l2appendconsnl1l2consnappendl1l2lesn0falsele0mtruelesnsmlenmacadlessElementsltlessElt0lessEltntoListtlessEltnlengthtoListtlessEltnlelengthtoListtnlessEltnlengthllessEltnlelengthlnlessEltniflelengthlnlelengthtoListtnltniffalsefalseltnlessEltsnlengthconsnllengthltoListnodet1nt2toListt2toListnodet1nt2toListt1toListnodet1nt2appendtoListt1consntoListt2appendconsnl1l2appendl1l2lesnsmlenmtruelessElementsltlessElt0falseiffalsefalseltnlessEltsnlessEltniflelengthlnlelengthtoListtnltntruelessEltnlelengthlnfalselessEltnlengthlfalselessEltnlelengthtoListtnfalselesnsmlenmtruele22lessEltnlengthtoListtfalselengthconsnllengthltruelength11lessEltntoListtfalsetoListnodet1nt2toListt2toListnodet1nt2toListt1truetoList11toListnodet1nt2appendtoListt1consntoListt2falseappendconsnl1l2appendl1l2trueappend21