364473 enclosure 3-3 invasion
The black formation is the 3-6,4-4,7-3 enclosure.
Here this ko can be considered a normal result. If Black wants to prevent this, and kill White, it typically involves playing in a more aggressive way, relying on local strength.
This is perhaps Black's strongest attempt to prevent White from living. However, White forms a seki with no problems.
Almost any Black move threatens the life of . is a skillful attempt. White goes for ko again. If elsewhere, then White will play a.
In conclusion, White should not be in a rush to invade here, since much depends on the outside support. If Black adds another move, it is difficult to do so without a sense of being overconcentrated.