How to use lightLevel() Forge 1.17.1

[Gianka1485]

I am making a block which I want to emit lighting, but I don't understand how it really works, all it says is that it needs

.lightLevel(ToIntFunction<BlockState> p_60954_)

but I don't understand what parameter to put in the missing, it may seem silly, but it would help me a lot if you explained.

[Luis_ST]

for an example look into the BlockBehaviour.Properties class, there is a default implementation with return 0