user_schemes->end();
      };
      auto end = std::remove_if(all_schemes->begin(), all_schemes->end(),
                                is_requested_scheme);
      all_schemes->erase(end, all_schemes->end());
    }
  }

  return all_schemes;
}

static std::vector<std::string> GetSchemes() {
  static std::vector<std::string>* schemes = GetSchemesFromUserOrEnv();