def ignore?(buf)
      return true if /^\s*$/ =~ buf
      return false if Readline::HISTORY.empty?

      buffer[Readline::HISTORY.length - 1] == buf
    end
def ignore?(buf)
      return true if /^\s*$/ =~ buf
      return false if Readline::HISTORY.empty?

      buffer[Readline::HISTORY.length - 1] == buf
    end
Whether a specific command should not be stored in history.

 For now, empty lines and consecutive duplicates.