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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 magic_postpone_execution(self, line):
 """ Postpone execution of instructions until explicitly run Usage: Call this magic with `true` or nothing to postpone execution, or call with `false` to execute each instruction when evaluated. This defaults to True. Note that each cell is executed only executed after all lines in the cell have been evaluated properly. `%postpone_execution` or `%postpone_execution true` or `%postpone_execution false` """

        line = line.strip().lower()
        if not line or line == 'true':
            self.interpreter.postpone_execution = True
        elif line == 'false':
            self.interpreter.postpone_execution = False
        else:
            stream_content = {'name': 'stderr', 'text': "unknwon value '{}'".format(line)}
            self.send_response(self.iopub_socket, 'stream', stream_content)
            return {'status': 'error',
                    'execution_count': self.execution_count,
                    'ename': ValueError.__name__,
                    'evalue': "unknwon value '{}'".format(line),
                    'traceback': '???'}