protected void mark(final int lit) {
        final CLVar v = var(lit);
        assert v.mark() == 0;
        v.setMark(sign(lit));
        this.seen.push(lit);
    }
protected void mark ( final int lit ) { final CLVar v = var ( lit ) ; assert v . mark ( ) == 0 ; v . setMark ( sign ( lit ) ) ; this . seen . push ( lit ) ; }
Marks a given literal.
@param lit the literal