    # File lib/prawn/font.rb, line 48
        def font(name=nil, options={})
          return((defined?(@font) && @font) || font("Helvetica")) if name.nil?

          raise Errors::NotOnPage if pages.empty? && !page.in_stamp_stream?
          new_font = find_font(name, options)

          if block_given?
            save_font do
              set_font(new_font, options[:size])
              yield
            end
          else
            set_font(new_font, options[:size])
          end

          @font
        end