question: How to set experiment name such that it can be some unique name instead of version_0, ... etc.
context: I'm currently running a lot of experiments and in order to track all of them in tensorboard I have to rename each experiment folder by hand (e.g. lightning_logs/version_0 -> lightning_logs/{unique_informative_exp_name}).
  However, it would be better if I could pass the as an argument to Trainer.
  I searched documentation thoroughly, but couldn't find anything related to names of experiments (I found only default_root_dir argument, however, it's not that interesting)
  The question is follows :
  Is there a way to set experiment name on program level? I'm using default logger.
answer: You can pass Trainer a custom logger with the version specified.
  from pytorch_lightning.loggers import TensorBoardLogger
  
  logger = TensorBoardLogger("default_root_dir", version="your_version", name="my_model")
  trainer = Trainer(logger=logger)
  Here is the api of TensorBoardLogger