SwitchAttachment(string cloneName, string revitYear)
        {
            var clone = PyRevit.GetRegisteredClone(cloneName);

            if (revitYear != null)
            {
                int revitYearNumber = 0;
                if (int.TryParse(revitYear, out revitYearNumber))
                {
                    var attachment = PyRevit.GetAttached(revitYearNumber);
                    if (attachment != null)
                    {
                        if (attachment.Engine != null)
                        {
                            PyRevit.Attach(attachment.Product.ProductYear,
                                           clone,
                                           engineVer: attachment.Engine.Version,
                                           allUsers: attachment.AllUsers);
                        }
                        else
                        {
                            throw new pyRevitException(
                                      string.Format("Can not determine attachment engine for Revit \"{0}\"",
                                                    revitYear)
                                      );
                        }
                    }
                    else
                    {
                        throw new pyRevitException(
                                  string.Format("Can not determine existing attachment for Revit \"{0}\"",
                                                revitYear)
                                  );
                    }
                }
                else
                {
                    throw new pyRevitException(string.Format("Invalid Revit year \"{0}\"", revitYear));
                }
            }
            else
            {
                // read current attachments and reattach using the same config with the new clone
                foreach (var attachment in PyRevit.GetAttachments())
                {
                    if (attachment.Engine != null)
                    {
                        PyRevit.Attach(
                            attachment.Product.ProductYear,
                            clone,
                            engineVer: attachment.Engine.Version,
                            allUsers: attachment.AllUsers);
                    }
                    else
                    {
                        throw new pyRevitException("Can not determine attachment engine.");
                    }
                }
            }
        }
        RunPythonCommand(string inputCommand, string targetFile, string revitYear, PyRevitRunnerOptions runOptions)
        {
            // determine if script or command

            var modelFiles = new List <string>();

            // make sure file exists
            if (targetFile != null)
            {
                CommonUtils.VerifyFile(targetFile);
            }

            if (inputCommand != null)
            {
                // determine target revit year
                int revitYearNumber = 0;
                // if revit year is not specified try to get from model file
                if (revitYear == null)
                {
                    if (targetFile != null)
                    {
                        try {
                            revitYearNumber = new RevitModelFile(targetFile).RevitProduct.ProductYear;
                            // collect model names also
                            modelFiles.Add(targetFile);
                        }
                        catch (Exception ex) {
                            logger.Error(
                                "Revit version must be explicitly specifies if using a model list file. | {0}",
                                ex.Message
                                );
                        }
                    }
                    // if no revit year and no model, run with latest revit
                    else
                    {
                        revitYearNumber = RevitProduct.ListInstalledProducts().Max(r => r.ProductYear);
                    }
                }
                // otherwise, grab the year from argument
                else
                {
                    revitYearNumber = int.Parse(revitYear);
                    // prepare model list of provided
                    if (targetFile != null)
                    {
                        try {
                            var modelVer = new RevitModelFile(targetFile).RevitProduct.ProductYear;
                            if (revitYearNumber < modelVer)
                            {
                                logger.Warn("Model is newer than the target Revit version.");
                            }
                            else
                            {
                                modelFiles.Add(targetFile);
                            }
                        }
                        catch {
                            // attempt at reading the list file and grab the model files only
                            foreach (var modelPath in File.ReadAllLines(targetFile))
                            {
                                if (CommonUtils.VerifyFile(modelPath))
                                {
                                    try {
                                        var modelVer = new RevitModelFile(modelPath).RevitProduct.ProductYear;
                                        if (revitYearNumber < modelVer)
                                        {
                                            logger.Warn("Model is newer than the target Revit version.");
                                        }
                                        else
                                        {
                                            modelFiles.Add(modelPath);
                                        }
                                    }
                                    catch {
                                        logger.Error("File is not a valid Revit file: \"{0}\"", modelPath);
                                    }
                                }
                                else
                                {
                                    logger.Error("File does not exist: \"{0}\"", modelPath);
                                }
                            }
                        }
                    }
                }

                // now run
                if (revitYearNumber != 0)
                {
                    // determine attached clone
                    var attachment = PyRevit.GetAttached(revitYearNumber);
                    if (attachment == null)
                    {
                        logger.Error("pyRevit is not attached to Revit \"{0}\". " +
                                     "Runner needs to use the attached clone and engine to execute the script.",
                                     revitYear);
                    }
                    else
                    {
                        // determine script to run
                        string commandScriptPath = null;

                        if (!CommonUtils.VerifyPythonScript(inputCommand))
                        {
                            logger.Debug("Input is not a script file \"{0}\"", inputCommand);
                            logger.Debug("Attempting to find run command matching \"{0}\"", inputCommand);

                            // try to find run command in attached clone being used for execution
                            // if not found, try to get run command from all other installed extensions
                            var targetExtensions = new List <PyRevitExtension>();
                            if (attachment.Clone != null)
                            {
                                targetExtensions.AddRange(attachment.Clone.GetExtensions());
                            }
                            targetExtensions.AddRange(PyRevit.GetInstalledExtensions());

                            foreach (PyRevitExtension ext in targetExtensions)
                            {
                                logger.Debug("Searching for run command in: \"{0}\"", ext.ToString());
                                if (ext.Type == PyRevitExtensionTypes.RunnerExtension)
                                {
                                    try {
                                        var cmdScript = ext.GetRunCommand(inputCommand);
                                        if (cmdScript != null)
                                        {
                                            logger.Debug("Run command matching \"{0}\" found: \"{1}\"",
                                                         inputCommand, cmdScript);
                                            commandScriptPath = cmdScript;
                                            break;
                                        }
                                    }
                                    catch {
                                        // does not include command
                                        continue;
                                    }
                                }
                            }
                        }
                        else
                        {
                            commandScriptPath = inputCommand;
                        }

                        // if command is not found, stop
                        if (commandScriptPath == null)
                        {
                            throw new pyRevitException(
                                      string.Format("Run command not found: \"{0}\"", inputCommand)
                                      );
                        }

                        // RUN!
                        var execEnv = PyRevitRunner.Run(
                            attachment,
                            commandScriptPath,
                            modelFiles,
                            runOptions
                            );

                        // print results (exec env)
                        PyRevitCLIAppCmds.PrintHeader("Execution Environment");
                        Console.WriteLine(string.Format("Execution Id: \"{0}\"", execEnv.ExecutionId));
                        Console.WriteLine(string.Format("Product: {0}", execEnv.Revit));
                        Console.WriteLine(string.Format("Clone: {0}", execEnv.Clone));
                        Console.WriteLine(string.Format("Engine: {0}", execEnv.Engine));
                        Console.WriteLine(string.Format("Script: \"{0}\"", execEnv.Script));
                        Console.WriteLine(string.Format("Working Directory: \"{0}\"", execEnv.WorkingDirectory));
                        Console.WriteLine(string.Format("Journal File: \"{0}\"", execEnv.JournalFile));
                        Console.WriteLine(string.Format("Manifest File: \"{0}\"", execEnv.PyRevitRunnerManifestFile));
                        Console.WriteLine(string.Format("Log File: \"{0}\"", execEnv.LogFile));
                        // report whether the env was purge or not
                        if (execEnv.Purged)
                        {
                            Console.WriteLine("Execution env is successfully purged.");
                        }

                        // print target models
                        if (execEnv.ModelPaths.Count() > 0)
                        {
                            PyRevitCLIAppCmds.PrintHeader("Target Models");
                            foreach (var modelPath in execEnv.ModelPaths)
                            {
                                Console.WriteLine(modelPath);
                            }
                        }

                        // print log file contents if exists
                        if (File.Exists(execEnv.LogFile))
                        {
                            PyRevitCLIAppCmds.PrintHeader("Execution Log");
                            Console.WriteLine(File.ReadAllText(execEnv.LogFile));
                        }
                    }
                }
            }
        }