def coreSynScore(synT1, synT2):
    """Given two tuples representing the core genes surrounding each of
two genes, determine the number of shared core genes in each. Return
this, divided by the minimum of the two tuple lengths. Values will be
between 0 and 1.

    """
    minNumSurrounding = min(len(synT1), len(synT2))
    if minNumSurrounding == 0:
        return 0
    else:
        ct = 0
        for cgene in synT1:
            if cgene in synT2:
                ct += 1
        return ct / minNumSurrounding
