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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):
 """Return the value in the point ``x``."""

        if self.prior is None:
            tmp = self.domain.element((np.exp(x) - 1)).inner(self.domain.one())
        else:
            tmp = (self.prior * (np.exp(x) - 1)).inner(self.domain.one())
        return tmp