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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 find_metabolites_not_consumed_with_open_bounds(model):
 """ Return metabolites that cannot be consumed with open boundary reactions. When all metabolites can be secreted, it should be possible for each and every metabolite to be consumed in some form. Parameters model : cobra.Model The metabolic model under investigation. Returns ------- list Those metabolites that could not be consumed. """

    mets_not_consumed = list()
    helpers.open_exchanges(model)
    for met in model.metabolites:
        with model:
            exch = model.add_boundary(
                met, type="irrex", reaction_id="IRREX", lb=-1000, ub=0)
            solution = helpers.run_fba(model, exch.id, direction="min")
            if np.isnan(solution) or abs(solution) < TOLERANCE_THRESHOLD:
                mets_not_consumed.append(met)
    return mets_not_consumed