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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def getKeyForAPI(cls, siteStore, apiName):
 """ Get the API key for the named API, if one exists. @param siteStore: The site store. @type siteStore: L{axiom.store.Store} @param apiName: The name of the API. @type apiName: C{unicode} (L{APIKey} constant) @rtype: L{APIKey} or C{NoneType} """

        return siteStore.findUnique(
            cls, cls.apiName == apiName, default=None)