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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _package_to_staging(staging_package_url):
 """Repackage this package from local installed location and copy it to GCS. Args: staging_package_url: GCS path. """

    import google.datalab.ml as ml

    # Find the package root. __file__ is under [package_root]/mltoolbox/_structured_data/this_file
    package_root = os.path.abspath(
        os.path.join(os.path.dirname(__file__), '../../'))
    setup_path = os.path.abspath(
        os.path.join(os.path.dirname(__file__), 'master_setup.py'))
    tar_gz_path = os.path.join(staging_package_url, 'staging', 'trainer.tar.gz')

    print('Building package and uploading to %s' % tar_gz_path)
    ml.package_and_copy(package_root, setup_path, tar_gz_path)

    return tar_gz_path