See &quot; left(left(left(a right)right)right) &quot; , &quot; left(stack{a#b#c}right) &quot; , &quot; left(a over b right). &quot;
Например: &quot; left(left(left(a right)right)right) &quot; , &quot; left(stack{a#b#c}right) &quot; и &quot; left(a over b right) &quot; .