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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 _stream_annotation(file_name, pb_dir):
 """ Stream an entire remote annotation file from physiobank Parameters file_name : str The name of the annotation file to be read. pb_dir : str The physiobank directory where the annotation file is located. """

    # Full url of annotation file
    url = posixpath.join(config.db_index_url, pb_dir, file_name)

    # Get the content
    response = requests.get(url)
    # Raise HTTPError if invalid url
    response.raise_for_status()

    # Convert to numpy array
    ann_data = np.fromstring(response.content, dtype=np.dtype('<u1'))

    return ann_data