class Redis::Distributed

def zdiffstore(destination, *keys, **options)

and store the resulting sorted set in a new key.
Compute the difference between the first and all successive input sorted sets 
def zdiffstore(destination, *keys, **options)
  keys.flatten!(1)
  ensure_same_node(:zdiffstore, [destination] + keys) do |node|
    node.zdiffstore(destination, keys, **options)
  end
end