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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 build_grid(self):
 """Create LV grid graph """


        # add required transformers
        build_grid.transformer(self)

        # add branches of sectors retail/industrial and agricultural
        build_grid.build_ret_ind_agr_branches(self.grid_district)

        # add branches of sector residential
        build_grid.build_residential_branches(self.grid_district)