# File lib/chartkick.rb, line 17
  def chart_json
    if is_a?(Hash) && (key = keys.first) && key.is_a?(Array) && key.size == 2
      group_by { |k, _v| k[0] }.map do |name, data|
        {name: name, data: data.map { |k, v| [k[1], v] }}
      end
    else
      self
    end.to_json
  end