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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 get_document(self, id):
 """ Retrieves a particular document from this project. """

        obj_list = self.document_list
        matches = [i for i in obj_list if str(i.id) == str(id)]
        if not matches:
            raise DoesNotExistError("The resource you've requested does not \
exist or is unavailable without the proper credentials.")
        return matches[0]