from django import template

register = template.Library()

@register.filter
def range(value, arg=None):
    """
    Return a list containing an arithmetic progression of integers.
    
    Usage:
        {% for i in 5|range %}
            {{ i }} : 0,1,2,3,4
        {% endfor %}
        
        {% for i in 5|range:10 %}
            {{ i }} : 5,6,7,8,9
        {% endfor %}
    """
    if arg is not None:
        start = int(value)
        end = int(arg)
    else:
        start = 0
        end = int(value)
    
    return list(range(start, end))
