valid but not strictly correct inputs
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1. lots of whitespace between numbers or after numbers
2. valid %d input (positive sign, or fewer or more 0's)
3. valid %hhx input (as in 2)
4. terminating line with no \n

error-handling (invalid inputs)
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5. byte counts off
6. missing terminal line
7. >1 partial lines
8. partial followed by full line
9. no byte count at all
10. terminal line then full/partial lines
11. scanf failure -- bad hexadecimal digits
12. scanf failure -- bad decimal in byte count
13. line with too many hexadecimal digits