gistfile1.rb

    # Return true if we're inside a conditional block, false otherwise.
    #  
    def in_conditional?
      return @conditional_stack.length > 1
    end

    # Return true if we're inside a true conditional block (one that
    # evaluated true and should be executed).
    #
    def in_true_conditional?
      return in_conditional? && @conditional_stack.last == true 
    end

    # Return true if we're inside a false conditional block (one that
    # evaluated false and should not be executed).
    #  
    def in_false_conditional?
      return in_conditional? && @conditional_stack.last == false
    end

    # Return true if we're inside a nil conditional block (one whose evaluation 
    # doesn't matter because it was precluded by an outer conditional block
    # that was false)
    #  
    def in_nil_conditional?
      return in_conditional? && @conditional_stack.last == nil
    end