diff --git a/lib/desugaring.rb b/lib/desugaring.rb
index 8d52908..588c30e 100644
--- a/lib/desugaring.rb
+++ b/lib/desugaring.rb
@@ -21,7 +21,7 @@ def all_the_sugar(recipients, event, message)
   # Copy the contents of the previous method here and remove this sugar.
   #
   def desugared_poetry(recipients, event, message)
-    implement_me!
+    mail(message,to: recipients.map(&:email),subject: "You’re invited to #{event.title} on #{event.date}")
   end
 
   # Ruby allows you to pass arguments identified by name instead of just by position. They are really just
@@ -36,7 +36,7 @@ def desugared_poetry(recipients, event, message)
   # Copy the contents of the previous method here and remove this sugar.
   #
   def desugared_named_args(recipients, event, message)
-    implement_me!
+    mail(message,{to: recipients.map(&:email),subject: "You’re invited to #{event.title} on #{event.date}"})
   end
 
   # Ruby’s general syntax for hashes is `{key => value, key => value, ...}`. Because it is so common to use
@@ -51,7 +51,7 @@ def desugared_named_args(recipients, event, message)
   # Copy the contents of the previous method here and remove this sugar.
   #
   def desugared_symbol_keys(recipients, event, message)
-    implement_me!
+    mail(message,{:to => recipients.map(&:email),:subject => "You’re invited to #{event.title} on #{event.date}"})
   end
 
   # You may be wondering how `map(&:email)` works. When you precede the last argument of a method call with
@@ -70,7 +70,7 @@ def desugared_symbol_keys(recipients, event, message)
   # Copy the contents of the previous method here and remove this sugar.
   #
   def desugared_attr_proc(recipients, event, message)
-    implement_me!
+    mail(message,{:to => recipients.map{|recipients| recipients.email },:subject => "You’re invited to #{event.title} on #{event.date}"})
   end
 
   # You may recall from the Ruby koans that when you put `#{something}` in a `"`-delimited string, Ruby will
@@ -88,7 +88,7 @@ def desugared_attr_proc(recipients, event, message)
   # Copy the contents of the previous method here and remove this sugar.
   #
   def desugared_interpolation(recipients, event, message)
-    implement_me!
+    mail(message,{:to => recipients.map{|recipients| recipients.email},:subject => "You’re invited to " + event.title.to_s + " on " + event.date.to_s})
   end
 
   # Ruby tracks local variables lexically at compile time. Wherever you say `x = y`, the compiler assumes that
@@ -110,7 +110,7 @@ def desugared_interpolation(recipients, event, message)
   # (Think: which names are local variables, and which are not?)
   #
   def desugared_implicit_self(recipients, event, message)
-    implement_me!
+    self.mail(message,{:to => recipients.map{|recipients| recipients.email},:subject => "You’re invited to " + event.title.to_s + " on " + event.date.to_s})
   end
 
   # In Ruby, unlike Python, there are no properties distinct from method calls. When you say `x.y`, you are
@@ -131,7 +131,7 @@ def desugared_implicit_self(recipients, event, message)
   # but structurally quite similar!
   #
   def desugared_implicit_parens(recipients, event, message)
-    implement_me!
+    self.mail(message,{:to => recipients.map{|recipients| recipients.email},:subject => "You’re invited to " + event.title().to_s() + " on " + event.date().to_s()})
   end
 
   # In Ruby, every value is an object and every action is a method call. That includes operators. A binary
@@ -153,7 +153,11 @@ def desugared_implicit_parens(recipients, event, message)
   #   get added before the things on the right. (a + b + c) means ((a + b) + c), NOT (a + (b + c)).
   #
   def desugared_operators(recipients, event, message)
-    implement_me!
+    self.mail(message,{
+      :to => recipients.map{|recipients| recipients.email},
+      :subject => ((("You’re invited to ".+(event.title().to_s())).+(" on "))).+(event.date().to_s())
+      })
+    #self.mail(message,{:to => recipients.map{|recipients| recipients.email},:subject => "You’re invited to". + (event.title().to_s()) + "on". + (event.date().to_s())})
   end
 
   # Compare that to the version at the top.
diff --git a/lib/retail_transaction.rb b/lib/retail_transaction.rb
index 1bfa0e3..e25e322 100644
--- a/lib/retail_transaction.rb
+++ b/lib/retail_transaction.rb
@@ -39,6 +39,7 @@ def paid?
     state :processing_payment
     state :payment_declined
     state :settled
+    state :refunded
 
     event :check_out do
       transitions from: :ringing_up, to: :collecting_payment,
@@ -61,5 +62,10 @@ def paid?
     event :payment_declined do
       transitions from: :processing_payment, to: :payment_declined
     end
+
+    event :refund do
+      transitions from: :settled, to: :refunded
+    end
+
   end
 end
diff --git a/test/desugaring_test.rb b/test/desugaring_test.rb
index 24e8a7b..e029f94 100644
--- a/test/desugaring_test.rb
+++ b/test/desugaring_test.rb
@@ -44,7 +44,7 @@
           }
         ],
         exercise.mail_calls.first,
-        "Wrong arguments passed to mail method")
+        "Wrong arguments passed to mail method on variant #{variant}")
     end
   end
 
diff --git a/test/retail_transaction_test.rb b/test/retail_transaction_test.rb
index 823cbfe..ca78a7a 100644
--- a/test/retail_transaction_test.rb
+++ b/test/retail_transaction_test.rb
@@ -24,7 +24,6 @@
 
   describe "still ringing up, with items" do
     before(:each) { tx.add_item("broccoli") }
-
     it "can add more items" do
       tx.add_item("roller skates")
     end
@@ -86,6 +85,10 @@
       end
     end
 
+    it "cannot be refunded while payment is processing" do
+      assert_invalid_transition { tx.refund! }
+    end
+
     it "cannot re-process payment" do
       assert_invalid_transition { tx.process_payment! }
     end
@@ -120,6 +123,10 @@
       end
     end
 
+    it "cannot be refunded with declined payment" do
+      assert_invalid_transition { tx.refund! }
+    end
+
     it "can reopen and add more items" do
       tx.reopen!
       assert_equal true, tx.ringing_up?
@@ -152,5 +159,29 @@
     it "cannot be reopened" do
       assert_invalid_transition { tx.reopen! }
     end
+
+    it "can be refunded" do
+      tx.refund!
+      assert_equal true, tx.refunded?
+    end
+  end
+
+  describe "group for orders that are already refunded" do
+    before(:each) do
+      tx.add_item("bobcat")
+      tx.check_out!
+      tx.payment_info = "15 cents and a nail"
+      tx.process_payment!
+      tx.payment_authorized!
+      tx.refund!
+    end
+
+    it "cannot be refunded again" do
+      assert_invalid_transition { tx.refund! }
+    end
+
+    it "cannot be reopned again" do
+      assert_invalid_transition { tx.reopen! }
+    end
   end
 end