Solution for Interpolation .to_s ("String") via Robocop

solution_robocop_string_interpolation.rb

======= Problem with codes using interpolation #{url}====
lapse Offence from Robocop: C: 12: 32: Prefer to_s over string interpolation.
-------------------------
require 'nokogiri'
require 'open-uri'

class Browser
  attr_accessor :url

  def initialize
    @url = url
  end

  def fetch_content(url)
    html = Nokogiri::HTML(open("#{url}"))
    return html.at('body').inner_text
  end
end
===========
Solution: inside the method of fetch_content(url), remove the interpolation and add .to_s

like:    html = Nokogiri::HTML(open(url.to_s))