def top_tracks(country)
      return @top_tracks[country] unless @top_tracks[country].nil? || RSpotify.raw_response
      response = RSpotify.get("artists/#{@id}/top-tracks?country=#{country}")

      return response if RSpotify.raw_response
      @top_tracks[country] = response['tracks'].map { |t| Track.new t }
    end
def top_tracks(country)
      return @top_tracks[country] unless @top_tracks[country].nil? || RSpotify.raw_response
      response = RSpotify.get("artists/#{@id}/top-tracks?country=#{country}")

      return response if RSpotify.raw_response
      @top_tracks[country] = response['tracks'].map { |t| Track.new t }
    end
Returns artist's 10 top tracks by country.

 @param country [Symbol] An {http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 ISO 3166-1 alpha-2 country code}
 @return [Array<Track>]

 @example
           top_tracks = artist.top_tracks(:US)
           top_tracks.class       #=> Array
           top_tracks.size        #=> 10
           top_tracks.first.class #=> RSpotify::Track