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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 _call(self, x, out=None):
 """Take the power of ``x`` and write to ``out`` if given."""

        if out is None:
            return x ** self.exponent
        elif self.__domain_is_field:
            raise ValueError('cannot use `out` with field')
        else:
            out.assign(x)
            out **= self.exponent