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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 trigger(self, event, filter=None, update=None, documents=None, ids=None, replacements=None):
 """ Trigger the after_save hook on documents, if present. """


        if not self.has_trigger(event):
            return

        if documents is not None:
            pass
        elif ids is not None:
            documents = self.find_by_ids(ids, read_use="primary")
        elif filter is not None:
            documents = self.find(filter, read_use="primary")
        else:
            raise Exception("Trigger couldn't filter documents")

        for doc in documents:
            getattr(doc, event)(update=update, replacements=replacements)