title: Syntax error using form field in Sinatra
body: <p>I keep getting the following syntax error in my index.html.erb file. I'm using Ruby 2.1.2. and Sinatra 1.4.5. Any comments are appreciated.</p>
  
  <pre><code>syntax error, unexpected ')' @_out_buf = ''; @_out_buf.concat(( form_for(@user) do |f| ).to_s)
  
  &lt;%= form_for(@user) do |f| %&gt;
    &lt;div class="field"&gt;
      &lt;%= f.label :email %&gt;&lt;br /&gt;
      &lt;%= f.text_field :email %&gt;
    &lt;/div&gt;
    &lt;div class="actions"&gt;&lt;%= f.submit "Sign Up"%&gt;&lt;/div&gt;
  &lt;% end %&gt;
  </code></pre>