Loop over each item in a sequence or a mapping. For example, to display a list of users provided in a variable called users :

<h1>Members</h1>
    {% for user in users %}
        <li>{{ user.username|e }}</li>
    {% endfor %}
    
A sequence or a mapping can be either an array or an object implementing
the Traversable interface.
If you do need to iterate over a sequence of numbers, you can use the ..
operator:
        
{% for i in 0..10 %}
    * {{ i }}
{% endfor %}
The above snippet of code would print all numbers from 0 to 10.
It can be also useful with letters:
        
{% for letter in 'a'..'z' %}
    * {{ letter }}
{% endfor %}
The .. operator can take any expression at both sides:
        
{% for letter in 'a'|upper..'z'|upper %}
    * {{ letter }}
{% endfor %}
If you need a step different from 1, you can use the range function
instead.
The `loop` variable
Inside of a for loop block you can access some special variables:
    
The loop.length, loop.revindex, loop.revindex0, and
loop.last variables are only available for PHP arrays, or objects that
implement the Countable interface.
The `else` Clause
If no iteration took place because the sequence was empty, you can render a
replacement block by using else:
    {% for user in users %}
        <li>{{ user.username|e }}</li>
    {% else %}
        <li><em>no user found</em></li>
    {% endfor %}
Iterating over Keys
By default, a loop iterates over the values of the sequence. You can iterate
on keys by using the keys filter:
        
<h1>Members</h1>
    {% for key in users|keys %}
        <li>{{ key }}</li>
    {% endfor %}
Iterating over a Subset
You might want to iterate over a subset of values. This can be achieved using
the slice filter:
        
<h1>Top Ten Members</h1>
    {% for user in users|slice(0, 10) %}
        <li>{{ user.username|e }}</li>
    {% endfor %}