delete_lines
int delete_lines(int, int);
if (delete_lines(from, to) < 0)
if (delete_lines(first_addr, second_addr) < 0 ||
if (delete_lines(first_addr, second_addr) < 0)
if (delete_lines(1, addr_last) < 0)
if (delete_lines(current_addr, current_addr) < 0)