def METHOD_NAME(self, model):
    for j in model.fs.params.component_list:
        assert 1e-6 >= abs(
            value(
                model.fs.unit.inlet.flow_mass_comp[0, j]
                - model.fs.unit.treated.flow_mass_comp[0, j]
                - model.fs.unit.byproduct.flow_mass_comp[0, j]
            )
        )