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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):
 """Apply operators to ``x`` and sum."""

        if out is None:
            return self.prod_op(x)[0]
        else:
            wrapped_out = self.prod_op.range.element([out], cast=False)
            pspace_result = self.prod_op(x, out=wrapped_out)
            return pspace_result[0]