def dates(options = EMPTY_HASH)
      parameters = Specification.new(tag: Types::Tags).parameters(options)
      response = @client.get('/posts/dates', parameters)
      dates_with_counts_from(response)
    end
def dates(options = EMPTY_HASH)
      parameters = Specification.new(tag: Types::Tags).parameters(options)
      response = @client.get('/posts/dates', parameters)
      dates_with_counts_from(response)
    end
List dates with the number of bookmarks created on each

 @example
   dates = posts.dates(tag: ['one', 'two', 'three'])

 @param [Hash] options
   options to filter the results by
 @option options [Array<String>] :tag
   up to three tags to filter by

 @return [Hash{Date => Integer}]
   dates on which bookmarks were created associated with the number of
   bookmarks created on that date

 @api public

 @see https://pinboard.in/api/#posts_dates