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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 IdentifiersIndexer(instance):
 """Return a list of unique Identifier strings This populates the Identifiers Keyword index, but with some replacements to prevent the word-splitter etc from taking effect. """

    identifiers = instance.Schema()['Identifiers'].get(instance)
    return [safe_unicode(i['Identifier']) for i in identifiers]