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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 extract_frame(self):
 """ Pulls one complete frame off the buffer and returns it. If there is no complete message in the buffer, returns None. Note that the buffer can contain more than once message. You should therefore call this method in a loop (or use iterator functionality exposed by class) until None returned. @return: The next complete frame in the buffer. @rtype: L{stomp.frame.Frame} """

        # (mbytes, hbytes) = self._find_message_bytes(self.buffer)
        # if not mbytes:
        #     return None
        #
        # msgdata = self.buffer[:mbytes]
        # self.buffer = self.buffer[mbytes:]
        # hdata = msgdata[:hbytes]
        # # Strip off any leading whitespace from headers; this is necessary, because
        # # we do not (any longer) expect a trailing \n after the \x00 byte (which means
        # # it will become a leading \n to the next frame).
        # hdata = hdata.lstrip()
        # elems = hdata.split('\n')
        # cmd = elems.pop(0)
        # headers = {}
        #
        # for e in elems:
        #     try:
        #         (k,v) = e.split(':', 1) # header values may contain ':' so specify maxsplit
        #     except ValueError:
        #         continue
        #     headers[k.strip()] = v.strip()
        #
        # # hbytes points to the start of the '\n\n' at the end of the header,
        # # so 2 bytes beyond this is the start of the body. The body EXCLUDES
        # # the final byte, which is  '\x00'.
        # body = msgdata[hbytes + 2:-1]
        self._buffer.seek(self._pointer, 0)
        try:
            f = Frame.from_buffer(self._buffer)
            self._pointer = self._buffer.tell()
        except (IncompleteFrame, EmptyBuffer):
            self._buffer.seek(self._pointer, 0)
            return None

        return f