I want to know the answer to the following question:
To ensure a minimum density of signal transitions  remains in the bitsream, what does USB use?
All the background I'm provided with is that "To ensure a minimum density of signal transitions remains in the bitstream, USB uses bit stuffing; an extra 0 bit is inserted into the data stream after any appearance of six consecutive 1 bits.". Is that enough to answer the question?
Answer: yes