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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 hmget(self, *args):
 """ This command on the model allow getting many instancehash fields with only one redis call. You must pass hash name to retrieve as arguments. """

        if args and not any(arg in self._instancehash_fields for arg in args):
            raise ValueError("Only InstanceHashField can be used here.")

        return self._call_command('hmget', args)