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C and Unix as a prerequisite for Python? I don't think so. Python is much higher level and has richer features.

I think he is better of learning from more pythonic sources, and learning programming in general.

No. Not to learn C. These books, and others like it (for C and any other language (including Python)) have exercises.

The guy was looking for exercises.

You can implement the exercises in whatever language you're learning. Python, for example.