def resolve_url(url)
      begin
        # RestClient does all the response code handling and redirection.
        url = Resource.http_head_request(url)
        if url.nil?
          @@config.logger.warn "#{@iri}\t// #{url}"
        else
          @@config.logger.debug "Mapped #{@iri}\t-> #{url}"
        end
      rescue
        binding.pry if @@config.debug
        @@config.logger.error "unknown http error for #{@iri}"
        url = nil
      end
      url
    end
def resolve_url(url)
      begin
        # RestClient does all the response code handling and redirection.
        url = Resource.http_head_request(url)
        if url.nil?
          @@config.logger.warn "#{@iri}\t// #{url}"
        else
          @@config.logger.debug "Mapped #{@iri}\t-> #{url}"
        end
      rescue
        binding.pry if @@config.debug
        @@config.logger.error "unknown http error for #{@iri}"
        url = nil
      end
      url
    end
---
 HTTP methods
 @param url [String|URI] A URL that can be resolved via HTTP request
 @return [String|nil] the URL, after resolving redirections