PackedList gets count() and trim() methods
- the bit counting is relatively fast: under 0.2 seconds for 1M bits counted 1000 times - trim()'ing the final zero elements tested for a few cases, but might need more attention
- the bit counting is relatively fast: under 0.2 seconds for 1M bits counted 1000 times - trim()'ing the final zero elements tested for a few cases, but might need more attention