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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 parse_str(mmp_bytes, content_type, encoding='utf-8'):
 """Parse multipart document bytes into a tuple of BodyPart objects. Args: mmp_bytes: bytes Multipart document. content_type : str Must be on the form, ``multipart/form-data; boundary=<BOUNDARY>``, where ``<BOUNDARY>`` is the string that separates the parts of the multipart document in ``mmp_bytes``. In HTTP requests and responses, it is passed in the Content-Type header. encoding : str The coding used for the text in the HTML body. Returns: tuple of BodyPart Members: headers (CaseInsensitiveDict), content (bytes), text (Unicode), encoding (str). """

    return requests_toolbelt.multipart.decoder.MultipartDecoder(
        mmp_bytes, content_type, encoding
    ).parts