def absolute_url_from(page_url, current_url)
      return unless eligible_url?(page_url)
      parsed_uri = URI.join(current_url, page_url) rescue return
      return unless parsed_uri.hostname == @base_hostname
      parsed_uri.to_s
    end
def absolute_url_from(page_url, current_url)
      return unless eligible_url?(page_url)
      parsed_uri = URI.join(current_url, page_url) rescue return
      return unless parsed_uri.hostname == @base_hostname
      parsed_uri.to_s
    end
Initialize CrawlUrl
 @param [String] base_url
 @example Intitialize CrawlUrl with example.com as base_url
   CrawlUrl.new('example.com')
 Given a link it constructs the absolute path,
 if valid URL & URL has same domain as @resolved_base_url.
 @param [String] page_url url found on page
 @param [String] current_url current page url
 @return [String] with absolute path to resource
 @example Construct absolute URL for '/path', example.com
   cu = CrawlUrl.new('example.com')
   cu.absolute_url_from('/path', 'example.com/some/path')
   # => http://example.com/some/path