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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 file_open(self, fn):
 """Yields the opening text of a file section in multipart HTTP. Parameters fn : str Filename for the file being opened and added to the HTTP body """

        yield b'--'
        yield self.boundary.encode()
        yield CRLF
        headers = content_disposition(fn)
        headers.update(content_type(fn))
        for c in self._write_headers(headers):
            yield c