fails:Array#zip returns an array of arrays containing corresponding elements of each array
fails:Array#zip fills in missing values with nil
fails:Array#zip properly handles recursive arrays
fails:Array#zip calls #to_ary to convert the argument to an Array
fails:Array#zip uses #each to extract arguments' elements when #to_ary fails
fails:Array#zip calls block if supplied
fails:Array#zip does not return subclass instance on Array subclasses
