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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 lesson_nums(self):
 """A dict from brain name to the brain's curriculum's lesson number."""

        lesson_nums = {}
        for brain_name, curriculum in self.brains_to_curriculums.items():
            lesson_nums[brain_name] = curriculum.lesson_num

        return lesson_nums