diff --git a/lib/desugaring.rb b/lib/desugaring.rb
index 8d52908..5f4c48a 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 +153,9 @@ 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)})
   end
 
   # Compare that to the version at the top.
diff --git a/lib/retail_transaction.rb b/lib/retail_transaction.rb
index 1bfa0e3..45dd09f 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,
@@ -58,6 +59,10 @@ def paid?
       transitions from: :processing_payment, to: :settled
     end
 
+    event :refund do
+      transitions from: :settled, to: :refunded
+    end
+
     event :payment_declined do
       transitions from: :processing_payment, to: :payment_declined
     end
diff --git a/test/retail_transaction_test.rb b/test/retail_transaction_test.rb
index 823cbfe..bc0b4a1 100644
--- a/test/retail_transaction_test.rb
+++ b/test/retail_transaction_test.rb
@@ -103,6 +103,12 @@
       assert_equal false, tx.settled?
       assert_equal true,  tx.payment_declined?
     end
+    
+    it "cannot give refund" do
+          assert_raises do
+            rx.refund!
+        end
+    end
   end
 
   describe "with declined payment" do
@@ -138,19 +144,54 @@
       assert_equal false, tx.payment_declined?
       assert_equal true,  tx.processing_payment?
     end
+    
+    it "cannot give refund" do
+        assert_raises do
+          tx.refund!
+        end
+    end
   end
-
+  
   describe "that is settled" 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!
-    end
-
-    it "cannot be reopened" do
-      assert_invalid_transition { tx.reopen! }
-    end
+      before(:each) do
+          tx.add_item("bobcat")
+          tx.check_out!
+          tx.payment_info = "15 cents and a nail"
+          tx.process_payment!
+          tx.payment_authorized!
+      end
+      
+      it "cannot be reopened" do
+          assert_invalid_transition { tx.reopen! }
+      end
+      
+      it "can be refunded" do
+        tx.refund!
+        assert_equal false, tx.settled?
+        assert_equal true, tx.refunded?
+      end
   end
+  
+  describe "that is 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 refund a second time" do
+          assert_raises do
+              tx.refund!
+          end
+      end
+      
+      it "cannot reopen refunded order" do
+          assert_raises do
+              tx.reopen!
+          end
+      end
+    end
 end