Fimming a marijuana plant
Fimming is actually no different than topping, what fimming does is virtually the exact same thing only your leaving part of the new growth. This only takes of part of the new growth and actually topping the very very new growth which is very hard to see.
What this ends up doing is making it seem as if your getting 4 new tops right next to eachother when its actually only 2 at the very top (like topping) but since it was cut so closely to the next newest set of fanleaves 2 branches which would have formed there anyways seems to make it look like there is 4 new tops. Fimming can be easily performed on sativas (or any hybrids of sativa cannabis seeds crosses) as they tend to grow longer and less dense stems, which is usefull for such precise procedure.