class Rack::Session::Cookie::Base64::JSON

valid JSON composite type, either a Hash or an Array.
N.B. Unlike other encoding methods, the contained objects must be a

def decode(str) 

def decode(str)
  return unless str
  ::JSON.parse(super(str)) rescue nil
end

def encode(obj) 

def encode(obj)
  super(::JSON.dump(obj))
end