How to use the ai2thor.downloader function in ai2thor

def build_url(self):
        from ai2thor.build import arch_platform_map
        import ai2thor.build
        if platform.system() in BUILDS:
            return (BUILDS[platform.system()]['url'], BUILDS[platform.system()]['sha256'])
        else:
            url = None
            sha256_build = None
            git_dir = os.path.normpath(os.path.dirname(os.path.realpath(__file__)) + "/../.git")
            for commit_id in subprocess.check_output('git --git-dir=' + git_dir + ' log -n 10 --format=%H', shell=True).decode('ascii').strip().split("\n"):
                arch = arch_platform_map[platform.system()]

                try:
                    u = ai2thor.downloader.commit_build_url(arch, commit_id)
                    if os.path.isfile(self.executable_path(url=u)):
                        # don't need sha256 since we aren't going to download
                        url = u
                        break
                    elif ai2thor.downloader.commit_build_exists(arch, commit_id):
                        sha256_build = ai2thor.downloader.commit_build_sha256(arch, commit_id)
                        url = u
                        break
                except Exception:
                    pass

            if url is None:
                raise Exception("Couldn't find a suitable build url for platform: %s" % platform.system())

            # print("Got build for %s: " % (url))

return (BUILDS[platform.system()]['url'], BUILDS[platform.system()]['sha256'])
        else:
            url = None
            sha256_build = None
            git_dir = os.path.normpath(os.path.dirname(os.path.realpath(__file__)) + "/../.git")
            for commit_id in subprocess.check_output('git --git-dir=' + git_dir + ' log -n 10 --format=%H', shell=True).decode('ascii').strip().split("\n"):
                arch = arch_platform_map[platform.system()]

                try:
                    u = ai2thor.downloader.commit_build_url(arch, commit_id)
                    if os.path.isfile(self.executable_path(url=u)):
                        # don't need sha256 since we aren't going to download
                        url = u
                        break
                    elif ai2thor.downloader.commit_build_exists(arch, commit_id):
                        sha256_build = ai2thor.downloader.commit_build_sha256(arch, commit_id)
                        url = u
                        break
                except Exception:
                    pass

            if url is None:
                raise Exception("Couldn't find a suitable build url for platform: %s" % platform.system())

            # print("Got build for %s: " % (url))

            return (url, sha256_build)

def poll_ci_build(context):
    from ai2thor.build import platform_map
    import ai2thor.downloader
    import time

    commit_id = (
        subprocess.check_output("git log -n 1 --format=%H", shell=True)
        .decode("ascii")
        .strip()
    )
    for i in range(360):
        missing = False
        for arch in platform_map.keys():
            if (i % 5) == 0:
                print("checking %s for commit id %s" % (arch, commit_id))
            if ai2thor.downloader.commit_build_log_exists(arch, commit_id):
                print("log exists %s" % commit_id)
            else:
                missing = True
        if not missing:
            break
        time.sleep(10)

    for arch in platform_map.keys():
        if not ai2thor.downloader.commit_build_exists(arch, commit_id):
            print(
                "Build log url: %s"
                % ai2thor.downloader.commit_build_log_url(arch, commit_id)
            )
            raise Exception("Failed to build %s for commit: %s " % (arch, commit_id))

for arch in platform_map.keys():
            if (i % 5) == 0:
                print("checking %s for commit id %s" % (arch, commit_id))
            if ai2thor.downloader.commit_build_log_exists(arch, commit_id):
                print("log exists %s" % commit_id)
            else:
                missing = True
        if not missing:
            break
        time.sleep(10)

    for arch in platform_map.keys():
        if not ai2thor.downloader.commit_build_exists(arch, commit_id):
            print(
                "Build log url: %s"
                % ai2thor.downloader.commit_build_log_url(arch, commit_id)
            )
            raise Exception("Failed to build %s for commit: %s " % (arch, commit_id))