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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 owned_ecs(self):
        '''A list of the execution contexts owned by this component.'''
        with self._mutex:
            if not self._owned_ecs:
                self._owned_ecs = [ExecutionContext(ec,
                    self._obj.get_context_handle(ec)) \
                    for ec in self._obj.get_owned_contexts()]
        return self._owned_ecs