exact: exact match
icontains: case-insensitive containment test
startswith, istartswith: starts with (case-insensitive)
endswith, iendswith: ends with (case-insensitive)
gte, lte: greater than or equal to, less than or equal to
gt, lt: greater than, less than
in: membership check (e.g. age__in=4,50)
range: range check (e.g. age__range=20,30)