You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: xss_check.rb
    path of file: ./repos/API-fuzzer/lib/API_Fuzzer
    
    the code of the file until where you have to start completion: require 'API_Fuzzer/vulnerability'
require 'API_Fuzzer/error'
require 'API_Fuzzer/request'

module API_Fuzzer

  class InvalidURLError < StandardError; end

  class XssCheck
    attr_accessor :parameters

    ALLOWED_METHODS = [:get, :post].freeze
    PAYLOADS = []
    PAYLOAD_PATH = File.expand_pat
    
    def self.scan(options = {})
      @url = options[:url] || nil
      raise InvalidURLError, "[ERROR] URL missing in argument" unless @url
      @params = options[:params] || {}
      @cookies = options[:cookies] || {}
      @headers = options[:headers] || {}
      @json = options[:json] || false
      @vulnerabilities = []

      fetch_payloads
      PAYLOADS.each do |payload|
        fuzz_each_payload(payload)
      end
      @vulnerabilities.uniq { |vuln| vuln.description }
    end