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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 process_command_response(self, command, response):
 """ Takes an HAProxy socket command and its response and either raises an appropriate exception or returns the formatted response. """

        if response.startswith(b"Unknown command."):
            raise UnknownCommandError(command)
        if response == b"Permission denied.\n":
            raise PermissionError(command)
        if response == b"No such backend.\n":
            raise UnknownServerError(command)

        response = response.decode()
        return response.rstrip("\n")