Improve punctuation in Structs koans

lib/koans/07_structs.ex

@@ -5,12 +5,12 @@ defmodule Structs do
     defstruct [:name, :age ]
   end
 
-  koan "structs are defined and named after a module" do
+  koan "Structs are defined and named after a module" do
     person = %Person{}
     assert person == :__
   end
 
-  koan "you can access the fields of a struct" do
+  koan "You can access the fields of a struct" do
     nobody = %Person{}
     assert nobody.age == :__
   end
@@ -20,19 +20,19 @@ defmodule Structs do
     assert joe.name == :__
   end
 
-  koan "update fields with the pipe '|' operator" do
+  koan "Update fields with the pipe '|' operator" do
     joe = %Person{name: "Joe", age: 23}
     older = %{ joe | age: joe.age + 10}
     assert  older.age == :__
   end
 
-  koan "the original struct is not affected by updates" do
+  koan "The original struct is not affected by updates" do
     joe = %Person{name: "Joe", age: 23}
-    assert %{ joe | age: joe.age + 10}.age == 33
+    assert %{ joe | age: joe.age + 10}.age == :__
     assert joe.age == :__
   end
 
-  koan "you can pattern match into the fields of a struct" do
+  koan "You can pattern match into the fields of a struct" do
     %Person{age: age} = %Person{age: 22, name: "Silvia"}
     assert age == :__
   end
@@ -41,13 +41,16 @@ defmodule Structs do
     defstruct passengers: 0, maker: :boeing
   end
 
-  koan "or onto the type of the struct itself" do
-    assert is_a_plane(%Plane{passengers: 417, maker: :boeing}) == :__
+  def plane?(%Plane{}), do: true
+  def plane?(_), do: false
+
+  koan "Or onto the type of the struct itself" do
+    assert plane?(%Plane{passengers: 417, maker: :boeing}) == :__
+    assert plane?(%Person{}) == :__
   end
 
-  def is_a_plane(%Plane{}), do: true
 
-  koan "are basically maps" do
+  koan "Are basically maps" do
     silvia = %Person{age: 22, name: "Silvia"}
 
     assert Map.fetch!(silvia, :age) == :__