docs: def require_server(fn):
      """
      Checks if the user has called the task with a server name.
  
      Fabric tasks decorated with this decorator must be called like so::
  
          fab <server name> <task name>
  
      If no server name is given, the task will not be executed.
  
      """
      @wraps(fn)
      def wrapper(*args, **kwargs):
          if env.machine is None:
              abort(red('ERROR: You must provide a server name to call this'
                        ' task!'))
          return fn(*args, **kwargs)
      return wrapper