def each # FIXME
      if Hash === @tuple
        @tuple.each { |k, v| yield(k, v) }
      else
        @tuple.each_with_index { |v, k| yield(k, v) }
      end
    end
def each # FIXME
      if Hash === @tuple
        @tuple.each { |k, v| yield(k, v) }
      else
        @tuple.each_with_index { |v, k| yield(k, v) }
      end
    end
Iterate through the tuple, yielding the index or key, and the
 value, thus ensuring arrays are iterated similarly to hashes.