def findBestRun(runFitnesses):
    """
    Finds the best run that has the best fitness value and returns a tuple that
    contains the index of the run and the best fitness value.
    The function expects to receive a dictionary whose keys are indexes of runs and
    and values of fitness values of the corresponding run.
    """

    if len(runFitnesses) == 0:
        return ()

    minRunInd, minFitness = next(iter(runFitnesses.items()))
    minFitness = min(minFitness)

    for runInd in runFitnesses:
        if min(runFitnesses[runInd]) < minFitness:
            minFitness = min(runFitnesses[runInd])
            minRunInd = runInd

    return minRunInd, minFitness