Only works when all the sets are compatible---generated from the same map,
with the same number of districts. Sets of plans will be indexed by the
chain column.
# S3 method for redist_plans
rbind(..., deparse.level = 1)The redist_plans objects to combine. If named arguments are
provided, the names will be used in the chain column; otherwise, numbers
will be used for the chain column.
Ignored.
A new redist_plans object.