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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 _get_localized_fn(path, root_dir):
 """ Return absolute `path` relative to `root_dir`. When `path` == ``/home/xex/somefile.txt`` and `root_dir` == ``/home``, returned path will be ``/xex/somefile.txt``. Args: path (str):
 Absolute path beginning in `root_dir`. root_dir (str):
 Absolute path containing `path` argument. Returns: str: Local `path` when `root_dir` is considered as root of FS. """

    local_fn = path
    if path.startswith(root_dir):
        local_fn = path.replace(root_dir, "", 1)

    if not local_fn.startswith("/"):
        return "/" + local_fn

    return local_fn