def getIslandGenesInStrain(island, strainName, familiesO):
    """Given an island, a strain number, and our families object, return
all the genes in the island for that strain."""
    genesL = []
    for locFam in island.iterLocusFamilies(familiesO):
        genesL.extend(locFam.iterGenesByStrain(strainName))
    return genesL
