is a variable defined in `
Its value is
- Automatically becomes permanently buffer-local when set.
- This variable may be risky if used as a file-local variable.
Function that determines the next/previous diff region to show.
Should return t for regions to be ignored and nil otherwise.
This function gets a region number as an argument. The region number
is the one used internally by Ediff. It is 1 less than the number seen
by the user.