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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 lineReceived(self, line):
 """ A line was received. """

        if line.startswith(b"#"): # ignore it
            return
        if line.startswith(b"OK"):
            # if no command issued, then just 'ready'
            if self._ready:
                self._dq.pop(0).callback(self._currentResponse(line))
            else:
                self._ready = True
        if line.startswith(b"D "):
            self._bufferedData.append(line[2:].replace(b"%0A", b"\r")
                                      .replace(b"%0D", b"\n")
                                      .replace(b"%25", b"%"))
        if line.startswith(b"ERR"):
            self._dq.pop(0).errback(AssuanError(line))