diff --git a/lib/desugaring.rb b/lib/desugaring.rb
index 8d52908..bd9f05e 100644
--- a/lib/desugaring.rb
+++ b/lib/desugaring.rb
@@ -21,7 +21,10 @@ 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 +39,10 @@ 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 +57,10 @@ 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 +79,10 @@ 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{ |x| x.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
@@ -88,9 +100,14 @@ 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{ |x| x.email},
+      :subject => "You’re invited to " + event.title.to_s + " on " + event.date.to_s}
+    )
   end
 
+  #      :subject => "You’re invited to #{event.title} on #{event.date}"}
+
   # Ruby tracks local variables lexically at compile time. Wherever you say `x = y`, the compiler assumes that
   # `x` is a local variable, and implicitly declares it if it’s not already declared. You also create a local
   # variable when you make a method parameter or block parameter.
@@ -110,7 +127,10 @@ 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{ |x| x.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 +151,10 @@ 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(){ |x| x.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
@@ -153,9 +176,27 @@ 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(){|x|x.email()},
+      :subject=> 
+        (
+          (
+            (
+              "You’re invited to ".+(event.title().to_s())
+            ).+(
+              " on "
+              )
+          ).+(
+            event.date().to_s()
+          )
+        )
+      
+      }
+    )
   end
 
+  # =>, block {}, space in string, |x|
+
   # Compare that to the version at the top.
   #
   # Languages designers argue a lot -- excessively, perhaps -- about how much sugar is too much.
diff --git a/lib/door.rb b/lib/door.rb
index 0f99a74..8d9c534 100644
--- a/lib/door.rb
+++ b/lib/door.rb
@@ -16,29 +16,18 @@ class Door
     end
   end
 
-  aasm :deadbolt_lock, namespace: :deadbolt do
-    state :unlocked, initial: true
-    state :locked
-
-    event :lock_deadbolt do
-      transitions to: :locked
-    end
-
-    event :unlock_deadbolt do
-      transitions to: :unlocked
-    end
-  end
-
-  aasm :knob_lock, namespace: :knob do
-    state :unlocked, initial: true
-    state :locked
-
-    event :lock_knob do
-      transitions to: :locked
-    end
-
-    event :unlock_knob do
-      transitions to: :unlocked
+  for i in ["deadbolt", "knob"]
+    aasm (i + "_lock").to_sym, namespace: i.to_sym do
+      state :unlocked, initial: true
+      state :locked
+
+      event "lock_".concat(i).to_sym do
+        transitions to: :locked
+      end
+
+      event "unlock_".concat(i).to_sym do
+        transitions to: :unlocked
+      end
     end
   end
 end
diff --git a/lib/retail_transaction.rb b/lib/retail_transaction.rb
index 1bfa0e3..545e1f0 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 +62,9 @@ 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/retail_transaction_test.rb b/test/retail_transaction_test.rb
index 823cbfe..61eb9bb 100644
--- a/test/retail_transaction_test.rb
+++ b/test/retail_transaction_test.rb
@@ -103,6 +103,10 @@
       assert_equal false, tx.settled?
       assert_equal true,  tx.payment_declined?
     end
+
+    it "cannot be refunded" do
+      assert_invalid_transition{tx.refund!}
+    end
   end
 
   describe "with declined payment" do
@@ -138,6 +142,11 @@
       assert_equal false, tx.payment_declined?
       assert_equal true,  tx.processing_payment?
     end
+
+    it "cannot be refunded" do
+      assert_invalid_transition{tx.refund!}
+    end
+
   end
 
   describe "that is settled" do
@@ -152,5 +161,31 @@
     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 be refunded a second time" do
+      assert_invalid_transition { tx.refund! }
+    end
+
+    it "cannot be reopened" do
+      assert_invalid_transition { tx.reopen! } 
+    end
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index a343433..383ebf7 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -8,8 +8,8 @@
 
 # To see full test names when running tests:
 #
-# require "minitest/reporters"
-# Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
+require "minitest/reporters"
+Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 module Minitest::Assertions
   def assert_invalid_transition