def token_frequency
      tokens.each_with_object(Hash.new(0)) { |token, hash| hash[token] += 1 }.sort_by_value_desc
    end
def token_frequency
      tokens.each_with_object(Hash.new(0)) { |token, hash| hash[token] += 1 }.sort_by_value_desc
    end
Returns a sorted two-dimensional array where each member array is a token and its frequency.
 The array is sorted by frequency in descending order.

 @example
  Counter.new(%w[one two two three three three]).token_frequency
  # => [ ['three', 3], ['two', 2], ['one', 1] ]

 @return [Array<Array<String, Integer>>] An array of tokens and their frequencies