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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 obfn_g0var(self):
 """Variable to be evaluated in computing the TV regularisation term, depending on the ``gEvalY`` option value. """


        # Use of self.block_sep0(self.AXnr) instead of self.cnst_A0(self.X)
        # reduces number of calls to self.cnst_A0
        return self.var_y0() if self.opt['gEvalY'] else \
            self.block_sep0(self.AXnr)