xxxxxxxxxx
qs3 = qs1.union(qs2) # or qs3 = qs1 | qs2
qs3 = qs1.intersection(qs2) # or qs3 = qs1 & qs2
qs3 = qs1.difference(qs2) # no operator for this
# the above one might not work for some databases, you may use the following
qs3 = qs1.exclude(pk__in=qs2)