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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 content_type(self):
 """Returns the content-type value determined by file extension."""


        if hasattr(self, '_content_type'):
            return self._content_type

        filename, extension = os.path.splitext(self._file_path)
        if extension == '.csv':
            self._content_type = 'text/csv'
        elif extension == '.tsv':
            self._content_type = 'text/tab-separated-values'
        else:
            self._content_type = 'text/plain'

        return self._content_type