   @doc false
   def __mailbox__(messages) do
     length = length(messages)
+
     mailbox =
       messages
       |> Enum.take(@max_mailbox_length)
       |> Enum.map_join(@indent, &inspect/1)
+
     mailbox_message(length, @indent <> mailbox)
   end
 
   @doc false
   def __pins__([]), do: ""
+
   def __pins__(pins) do
     content =
       pins
       |> Enum.reverse()
       |> Enum.map_join(@indent, fn {name, var} -> "#{name} = #{inspect(var)}" end)
+
     "\nThe following variables were pinned:" <> @indent <> content
   end
 
   defp mailbox_message(0, _mailbox), do: "\nThe process mailbox is empty."
+
   defp mailbox_message(length, mailbox) when length > 10 do
-    "\nProcess mailbox:" <> mailbox <>
-      "\nShowing only #{@max_mailbox_length} of #{length} messages."
-  end
+    "\nProcess mailbox:" <>
+      mailbox <> "\nShowing only #{@max_mailbox_length} of #{length} messages."
+  end
+
   defp mailbox_message(_length, mailbox) do
     "\nProcess mailbox:" <> mailbox
   end

    quote do
      left = unquote(left)
      right = unquote(right)
      if ExUnit.Assertions.__equal__?(left, right) do
        assert false,
          left: left,

    quote do
      try do
        _ = unquote(expr)
        flunk("Expected to catch #{unquote(kind)}, got nothing")
      rescue
        e in [ExUnit.AssertionError] ->
          reraise(e, System.stacktrace())
      catch
        unquote(kind), we_got -> we_got
      end
