question: what is the default scheduler?
context: I see that there is an option to return just an optimizer in the configure_optimizers function. What will be the default scheduler in that case?
  BTW I tried very hard to find the answer in the docs and could not find it..
answer: There's no LR scheduler applied in this case: https://pytorch-lightning.readthedocs.io/en/latest/common/lightning_module.html#configure-optimizers