Add two styles underline2x and overline

README.markdown

@@ -46,6 +46,8 @@ Rainbow presenter adds the following methods to presented string:
 * `faint` (not well supported by terminal emulators)
 * `italic` (not well supported by terminal emulators)
 * `cross_out`, `strike`
+* `underline2x` (not well supported by terminal emulators)
+* `overline` (not well supported by terminal emulators)
 
 Text color can also be changed by calling a method named by a color:
 
@@ -101,10 +103,10 @@ of the following ways:
 
 * [ANSI color](https://en.wikipedia.org/wiki/ANSI_escape_code#Colors) name or [X11 color](https://en.wikipedia.org/wiki/X11_color_names) name as a symbol:
   `Rainbow("hello").color(:yellow)`.
-  This can be simplified to `Rainbow("hello").yellow`  
-  
-  See [Color list](#user-content-color-list) for all available color names.  
-  Note that ANSI colors can be changed in accordance with terminal setting.  
+  This can be simplified to `Rainbow("hello").yellow`
+
+  See [Color list](#user-content-color-list) for all available color names.
+  Note that ANSI colors can be changed in accordance with terminal setting.
   But X11 color is just a syntax sugar for RGB triplet. So you always see what you specified.
 
 * RGB triplet as separate values in the range 0-255:

lib/rainbow/null_presenter.rb

@@ -46,6 +46,14 @@ def cross_out
       self
     end
 
+    def underline2x
+      self
+    end
+
+    def overline
+      self
+    end
+
     def black
       self
     end

lib/rainbow/presenter.rb

@@ -15,7 +15,9 @@ class Presenter < ::String
       blink: 5,
       inverse: 7,
       hide: 8,
-      cross_out: 9
+      cross_out: 9,
+      underline2x: 21,
+      overline: 53
     }.freeze
 
     # Sets color of this text.
@@ -89,6 +91,14 @@ def cross_out
 
     alias strike cross_out
 
+    def underline2x
+      wrap_with_sgr(TERM_EFFECTS[:underline2x])
+    end
+
+    def overline
+      wrap_with_sgr(TERM_EFFECTS[:overline])
+    end
+
     def black
       color(:black)
     end

spec/unit/null_presenter_spec.rb

@@ -117,6 +117,18 @@ module Rainbow
       it_behaves_like "rainbow null string method"
     end
 
+    describe "#underline2x" do
+      subject { presenter.underline2x }
+
+      it_behaves_like "rainbow null string method"
+    end
+
+    describe "#overline" do
+      subject { presenter.overline }
+
+      it_behaves_like "rainbow null string method"
+    end
+
     it_behaves_like "presenter with shortcut color methods"
 
     describe "#method_missing" do

spec/unit/presenter_spec.rb

@@ -216,6 +216,28 @@ module Rainbow
       end
     end
 
+    describe '#underline2x' do
+      subject { presenter.underline2x }
+
+      it_behaves_like "rainbow string method"
+
+      it 'wraps with 21 code' do
+        subject
+        expect(StringUtils).to have_received(:wrap_with_sgr).with('hello', [21])
+      end
+    end
+
+    describe '#overline' do
+      subject { presenter.overline }
+
+      it_behaves_like "rainbow string method"
+
+      it 'wraps with 53 code' do
+        subject
+        expect(StringUtils).to have_received(:wrap_with_sgr).with('hello', [53])
+      end
+    end
+
     it_behaves_like "presenter with shortcut color methods"
   end
 end