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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 is_feasible_i(self, x, i):
 """return True if value ``x`` is in the invertible domain of variable ``i`` """

        lb = self._lb[self._index(i)]
        ub = self._ub[self._index(i)]
        al = self._al[self._index(i)]
        au = self._au[self._index(i)]
        return lb - al < x < ub + au