For your "point and plane test" it's easy enough to make your own tool's method without messing on with any base-classes...
def point_test(point, plane, cond=false)
### 'point' is the point to test,
### 'plane' is the plane to test and
### 'cond' allows you to return true/false IF point is ON the plane.
### NOW add your code here that see if the 'point' is on, in front or behind the 'plane'
### returns 'behind' as 'true' or 'false', with a tweak for the 'cond' setting
if behind
return false
else
return true
end#if
end#def
Then in other code within your toolset use
self.point_test(point, plane, true)
where 'point' is to be tested for its relationship with 'plane', and here the third argument 'true' says to take 'point' as being 'in front' even if it's ON the plane too... [you would use no third argument or 'false' if point ON plane is to be 'invalid']