def _renumber_formula(line, increase):
    """Increase formula id on the given ltlcross-log line

    Parameters
    ==========
    `line` — line from ltlcross log with formula to be translated.
    `increase` — number of which we should increase the formula id
    """
    splitted = line.split(":")
    splitted[1] = str(int(splitted[1]) + increase)
    return ":".join(splitted)