next
Advances the iterator either forward or backward the specified number of steps. Negative values move backward, and positive values move forward. This is equivalent to repeatedly calling next() or previous().
Return
The character offset of the boundary position n boundaries away from the current one.
Parameters
n
The number of steps to move. The sign indicates the direction (negative is backwards, and positive is forwards).
Advances the iterator to the next boundary position.
Return
The position of the first boundary after this one.