http://www.regular-expressions.info/lookaround.html
It might be a good topic to test these method:
What do you thing about it, too regex specific for a general programmer exam?hasTransparentBounds
public boolean hasTransparentBounds()Queries the transparency of region bounds for this matcher.
This method returns true if this matcher uses transparent bounds, false if it uses opaque bounds.
See useTransparentBounds for a description of transparent and opaque bounds.
By default, a matcher uses opaque region boundaries.
Returns:
true iff this matcher is using transparent bounds, false otherwise.
The_Nick