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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(self, uid=None):
 """Example retrieve API method. """

        # Return resource collection

        if uid is None:
            return self.response_factory.ok(data=resource_db)

        # Return resource based on UID.

        try:
            record = [r for r in resource_db if r.get('id') == uid].pop()

        except IndexError:
            return self.response_factory.not_found(errors=['Resource with UID {} does not exist.'.format(uid)])

        return self.response_factory.ok(data=record)