try:
    from django.conf.urls import patterns, url
except ImportError:
    # Django < 1.4
    from django.conf.urls.defaults import patterns, url

urlpatterns = patterns('avatar.views',
    url(r'^add/$', 'add', name='avatar_add'),
    url(r'^change/$', 'change', name='avatar_change'),
    url(r'^delete/$', 'delete', name='avatar_delete'),
    url(r'^render_primary/(?P<user>[\w\d\.\-_]{3,30})/(?P<width>[\d]+)/(?P<height>[\d]+)/$', 'render_primary', name='avatar_render_primary'),
    url(r'^list/(?P<username>[\+\w\@\.]+)/$', 'avatar_gallery', name='avatar_gallery'),
    url(r'^list/(?P<username>[\+\w\@\.]+)/(?P<id>[\d]+)/$', 'avatar', name='avatar'),
)

from django.conf.urls import url

from avatar import views

urlpatterns = [
    url(r'^add/$', views.add, name='avatar_add'),
    url(r'^change/$', views.change, name='avatar_change'),
    url(r'^delete/$', views.delete, name='avatar_delete'),
    url(r'^render_primary/(?P<user>[\w\d\.\-_]{3,30})/(?P<width>[\d]+)/(?P<height>[\d]+)/$', views.render_primary, name='avatar_render_primary'),
    url(r'^list/(?P<username>[\+\w\@\.]+)/$', views.avatar_gallery, name='avatar_gallery'),
    url(r'^list/(?P<username>[\+\w\@\.]+)/(?P<id>[\d]+)/$', views.avatar, name='avatar'),
]

Update urls.py