/* Returns the requested block, or 0 if it is beyond the length (as if
* the number had 0s infinitely to the left). */
Blk getBlock(Index i) const { return i >= len ? 0 : blk[i]; }
/* Returns the requested block, or 0 if it is beyond the length (as if
* the number had 0s infinitely to the left). */
Blk getBlock(Index i) const { return i >= len ? 0 : blk[i]; }