whole_func_string: function initialize(shell) {
    shell.loadedExtensions = {};
  
    shell.registerCommand('extension', extensionCommand);
    shell.registerCommand('extensions', extensionsCommand);
  }
func_code_string: function initialize(shell) {
    shell.loadedExtensions = {};
  
    shell.registerCommand('extension', extensionCommand);
    shell.registerCommand('extensions', extensionsCommand);
  }
func_documentation_string: Initializes the shell with extensions related functionality.