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: pairs.rb
    path of file: ./repos/cryptoexchange/lib/cryptoexchange/exchanges/aex/services
    
    the code of the file until where you have to start completion: module Cryptoexchange::Exchanges
  module Aex
    module Services
      class Pairs < Cryptoexchange::Services::Pairs
        PAIRS_URLS = [
          "#{Cryptoexchange::Exchanges::Aex::Market::API_URL}/ticker.php?c=all&mk_type=btc",
          "#{Cryptoexchange::Exchanges::Aex::Market::API_URL}/ticker.php?c=all&mk_type=usdt",
          "#{Cryptoexchange::Exchanges::Aex::Market::API_URL}/ticker
    
        def fetch
          PAIRS_URLS.map do |endpoint|
            output = fetch_via_api(endpoint)
            target = endpoint.split("=").last
            adapt(output, target)
          end.flatten
        end

        def adapt(output, target)
          pairs = []
          output.each do |key, value|
            pairs << Cryptoexchange::Models::MarketPair.new(
              base: key,
              target: target,
              market: Aex::Market::NAME
            )
          end
          pairs
        end
      end