title: How to use omit with Ansible and avoid any errors?
body: <p>I tried to use omit with an expression like this: </p>
  
  <pre><code>id: "{{ openstack_networks.id | default(omit) }}"
  </code></pre>
  
  <p>But it seems that it keeps failing with an exception when <code>openstack_networks</code> variable is not defined.</p>
  
  <p>What is the correct way to write this jinja2 filter?</p>
  
  <p>I want to omit the parameter in case openstack_networks.id does not exists.</p>