code: func setVal(stub shim.ChaincodeStubInterface) pb.Response {
  	args := stub.GetArgs()
  	if len(args) != 3 {
  		return shim.Error("setval expects two arguments")
  	}
  	var err error
  	if string(args[1]) == "pub" {
  		err = stub.PutState("pub", args[2])
  	} else if string(args[1]) == "priv" {
  		err = stub.PutPrivateData("col", "priv", args[2])
  	} else {
  		return shim.Error("Unknown key specified")
  	}
  	if err != nil {
  		return shim.Error(err.Error())
  	}
  	return shim.Success([]byte{})
  }
docs: // setVal sets the value of the KVS key