Add Refer To A Module Within Itself as an elixir til

elixir/refer-to-a-module-within-itself.md

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+# Refer To A Module Within Itself
+
+Elixir comes with the `__MODULE__` reserve word for referencing a module
+within itself. This is handy for things like structs.
+
+```elixir
+defmodule SomeNamespace.MyModule do
+  defstruct [:id]
+
+  def do_thing(%__MODULE__{}=thing) do
+    # ...
+  end
+end
+```
+
+You can use an alias in order to ditch `__MODULE__` and perhaps make your
+code a bit more human readable.
+
+```elixir
+defmodule SomeNamespace.MyModule do
+  alias __MODULE__, as: MyModule
+
+  defstruct [:id]
+
+  def do_thing(%MyModule{}=thing) do
+    # ...
+  end
+end
+```