<title>{% block title %}{% endblock %}</title>
<h1>{{ block('title') }}</h1>
{% block body %}{% endblock %}
The block function can also be used to display one block from another template:
{{ block('title', 'common_blocks.html') }}
Use the defined test to check if a block exists in the context of the current template:
{% if block('footer') is defined %}
...
{% endif %}
{% if block('footer', 'common_blocks.html') is defined %}
...
{% endif %}