title: How can I get the keys in a multidimensional hash in Ruby?
body: <p>So with a normal hash you can use this to get the keys:</p>
  
  <pre><code>hash.keys
  </code></pre>
  
  <p>How can I get the keys of the 2nd dimension of a multidimensional hash that looks like this:</p>
  
  <pre><code>{"&lt;id&gt;"=&gt;{"first_name"=&gt;"test", "last_name"=&gt;"test_l", "username"=&gt;"test_user", 
  "title"=&gt;"Sales Manager", "office"=&gt;"test", "email"=&gt;"test@test.com"}}
  </code></pre>
  
  <p><code>&lt;id&gt;</code> is unique for each item. </p>
  
  <p>So the keys I want from above are: <code>first_name, last_name, username, title, office and email</code></p>