       ...> end
       {:sum, [], [1, 2, 3]}
 
-  ## Elixir's AST (abstract syntax tree)
+  ## Elixir's AST (Abstract Syntax Tree)
 
   Any Elixir code can be represented using Elixir data structures.
   The building block of Elixir macros is a tuple with three elements,


      {:sum, [], [1, {:value, [], Elixir}, 3]}

  Which is not the expected result. For this, we use unquote:

      iex> value =
      ...>   quote do

      ...> end
      {:sum, [], [1, 13, 3]}

  If you want to unquote a value that is not a quoted expression,
  such as a map, you need to call `Macro.escape/1` before:

      iex> value = %{foo: :bar}
      iex> quote do
