def dzen
      return @@dzen unless @@dzen.nil?

      @@dzen = DZEN::Terminal.new if defined?(::TERMINAL) || !!ENV['TERMINAL']
      @@dzen = DZEN::Default.new unless @@dzen

      @@dzen
    end
def dzen
      return @@dzen unless @@dzen.nil?

      @@dzen = DZEN::Terminal.new if defined?(::TERMINAL) || !!ENV['TERMINAL']
      @@dzen = DZEN::Default.new unless @@dzen

      @@dzen
    end
Public: Gets the current DZEN instance.

 Define TERMINAL or ENV['TERMINAL'] to use DZEN::Terminal
 instead of DZEN::Default.

 Returns a newly created or currently existing DZEN instance.