code: def add_reaction_constraints(model, reactions, Constraint):
      
      constraints = []
      for rxn in reactions:
          expression = add(
              [c * model.variables[m.id] for m, c in rxn.metabolites.items()])
          constraints.append(Constraint(expression, lb=0, ub=0, name=rxn.id))
      model.add(constraints)
docs: Add the stoichiometric coefficients as constraints.
  
      Parameters
      ----------
      model : optlang.Model
          The transposed stoichiometric matrix representation.
      reactions : iterable
          Container of `cobra.Reaction` instances.
      Constraint : optlang.Constraint
          The constraint class for the specific interface.