def edit_emoji(emoji)
    @names_index ||= Hash.new
    @unicodes_index ||= Hash.new

    yield emoji

    emoji.aliases.each do |name|
      @names_index[name] = emoji
    end
    emoji.unicode_aliases.each do |unicode|
      @unicodes_index[unicode] = emoji
    end

    emoji
  end
Public: Yield an emoji to the block and update the indices in case its
aliases or unicode_aliases lists changed.