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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 target_data(self):
 """ The TargetData for this execution engine. """

        if self._td is not None:
            return self._td
        ptr = ffi.lib.LLVMPY_GetExecutionEngineTargetData(self)
        self._td = targets.TargetData(ptr)
        self._td._owned = True
        return self._td