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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 normalize_package_path(cls, package_path):
 """Returns a normalized version of the given package path. The root package might by denoted by '' or '.' and is normalized to ''. All other packages are of the form 'path' or 'path/subpath', etc. If the given path is either absolute or relative (includes the parent dir path signifier, '..'), then an error is raised since the path cannot be noramlized. :param string package_path: The Go package path to normalize. :raises: `ValueError` if the package path cannot be normalized. """

    if package_path.startswith(os.pardir + os.sep):
      raise ValueError('Relative package paths are not allowed. Given: {!r}'.format(package_path))
    if os.path.isabs(package_path):
      raise ValueError('Absolute package paths are not allowed. Given: {!r}'.format(package_path))
    return '' if not package_path or package_path == os.curdir else package_path.lstrip('/')