class Unicode::DisplayWidth

def self.decompress_index(index, level)
  index.flat_map{ |value|
    if level > 0
      if value.instance_of?(Array)
        value[15] ||= nil
        decompress_index(value, level - 1)
      else
        decompress_index([value] * 16, level - 1)
      end
    else
      if value.instance_of?(Array)
        value[15] ||= nil
        value
      else
        [value] * 16
      end
    end
  }
end