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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, content_type, filename=None):
 """Determine the content type from the current object. The return value will be determined in order of precedence: - The value passed in to this method (if not :data:`None`) - The value stored on the current blob - The default value ('application/octet-stream') :type content_type: str :param content_type: (Optional) type of content. :type filename: str :param filename: (Optional) The name of the file where the content is stored. :rtype: str :returns: Type of content gathered from the object. """

        if content_type is None:
            content_type = self.content_type

        if content_type is None and filename is not None:
            content_type, _ = mimetypes.guess_type(filename)

        if content_type is None:
            content_type = _DEFAULT_CONTENT_TYPE

        return content_type