public void PostProposal(int contestId, Product product, Supplier supplier)
 {
     List<Proposal> prop;
     if (!Proposals.ContainsKey(contestId))
     {
         prop = new List<Proposal>();
         Proposals.Add(contestId, prop);
     }
     else
     {
         prop = Proposals[contestId];
     }
     Proposal proposal = new Proposal { Product = product, Supplier = supplier };
     prop.Add(proposal);
 }
 public static bool RegisterSupplier(Supplier supplier)
 {
     return client.RegisterSupplier(supplier);
 }