title: Are the usage of parentheses in Typespecs optional?
body: <p>After looking over</p>
  <ol>
  <li><a href="https://hexdocs.pm/elixir/typespecs.html" rel="nofollow noreferrer">https://hexdocs.pm/elixir/typespecs.html</a></li>
  <li><a href="http://elixir-lang.org/getting-started/typespecs-and-behaviours.html" rel="nofollow noreferrer">http://elixir-lang.org/getting-started/typespecs-and-behaviours.html</a></li>
  </ol>
  <p>It appears following are all the same, is this just a code styling preference?</p>
  <pre><code>@type someCustomType() :: String.t()
  @type someCustomType() :: String.t
  @type someCustomType :: String.t()
  @type someCustomType :: String.t
  </code></pre>