def formatted
      copy = dup
      Helpers.rcompact(@formats)
      if copy.length < @formats.size
        copy.concat Array.new(@formats.size - copy.length)
      end
      copy
    end
def formatted
      copy = dup
      Helpers.rcompact(@formats)
      if copy.length < @formats.size
        copy.concat Array.new(@formats.size - copy.length)
      end
      copy
    end
Returns a copy of self with nil-values appended for empty cells that have
 an associated Format.
 This is primarily a helper-function for the writer classes.