 
   The second argument is a [cryptographic salt](https://en.wikipedia.org/wiki/Salt_(cryptography))
   which must be the same in both calls to `sign/4` and `verify/4`.
-  For instance, it may be called "user auth" when generating a token
-  that will be used to authenticate users on channels or on your APIs.
+  For instance, it may be called "user auth" and treated as namespace
+  when generating a token that will be used to authenticate users on
+  channels or on your APIs.
 
   The third argument can be any term (string, int, list, etc.)
   that you wish to codify into the token. Upon valid verification,


      iex> user_id    = 99
      iex> secret     = "kjoy3o1zeidquwy1398juxzldjlksahdk3"
      iex> user_salt  = "user salt"
      iex> token      = Phoenix.Token.sign(secret, user_salt, user_id)

  The mechanism for passing the token to the client is typically through a
  cookie, a JSON response body, or HTTP header. For now, assume the client has

  One is via the meta tag:

      <%= tag :meta, name: "channel_token",
                     content: Phoenix.Token.sign(@conn, "user auth", @current_user.id) %>

  Or an endpoint that returns it:

      def create(conn, params) do
        user = User.create(params)
        render(conn, "user.json",
               %{token: Phoenix.Token.sign(conn, "user auth", user.id), user: user})
      end

  Once the token is sent, the client may now send it back to the server
