code: func (list RequestCostList) decode() requestCostTable {
  	table := make(requestCostTable)
  	for _, e := range list {
  		table[e.MsgCode] = &requestCosts{
  			baseCost: e.BaseCost,
  			reqCost:  e.ReqCost,
  		}
  	}
  	return table
  }
docs: // decode converts a cost list to a cost table