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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_content_type(self):
 """mime type of the attachment part"""

        ctype = self.part.get_content_type()
        # replace underspecified mime description by a better guess
        if ctype in ['octet/stream', 'application/octet-stream',
                     'application/octetstream']:
            ctype = guess_mimetype(self.get_data())
        return ctype