def get_implicit_deps(self):
        """Return the executor's implicit dependencies, i.e. the nodes of
        the commands to be executed."""
        result = []
        build_env = self.get_build_env()
        for act in self.get_action_list():
            deps = act.get_implicit_deps(self.get_all_targets(),
                                         self.get_all_sources(),
                                         build_env)
            result.extend(deps)
        return result
Return the executor's implicit dependencies, i.e. the nodes of
        the commands to be executed.