def add_stderr(*args)
      args = args.flatten.compact
      args = args.first.split($/) if args.size == 1
      @stderr ||= []
      @stderr << args
      @stderr.flatten!
      self
    end
def add_stderr(*args)
      args = args.flatten.compact
      args = args.first.split($/) if args.size == 1
      @stderr ||= []
      @stderr << args
      @stderr.flatten!
      self
    end
Add STDERR output from the command executed via SSH.