def get_age(Rec, sitekey, keybase, Ages, DefaultAge):
    """
    finds the age record for a given site
    """
    site = Rec[sitekey]
    gotone = 0
    if len(Ages) > 0:
        for agerec in Ages:
            if agerec["er_site_name"] == site:
                if "age" in list(agerec.keys()) and agerec["age"] != "":
                    Rec[keybase + "age"] = agerec["age"]
                    gotone = 1
                if "age_unit" in list(agerec.keys()):
                    Rec[keybase + "age_unit"] = agerec["age_unit"]
                if "age_sigma" in list(agerec.keys()):
                    Rec[keybase + "age_sigma"] = agerec["age_sigma"]
    if gotone == 0 and len(DefaultAge) > 1:
        sigma = 0.5 * (float(DefaultAge[1]) - float(DefaultAge[0]))
        age = float(DefaultAge[0]) + sigma
        Rec[keybase + "age"] = '%10.4e' % (age)
        Rec[keybase + "age_sigma"] = '%10.4e' % (sigma)
        Rec[keybase + "age_unit"] = DefaultAge[2]
    return Rec
finds the age record for a given site