expandNext abstract method
Expands the current range with the next count characters.
Expands the current range to include the first count characters
following the current range, or as many as are available if
there are fewer than count characters following the current range.
The count must not be negative.
If it is zero, the range does not change.
Returns true if there are at least count characters following
the current range, and false if not.
Implementation
bool expandNext([int count = 1]);