question: what's the difference between `load_from_checkpoint ` and `resume_from_checkpoint`
context: I'm confused about two API:
  
  Module.load_from_checkpoint
  trainer.resume_from_checkpoint
answer: resume_from_checkpoint is used to resume the training using the checkpointed state_dicts. It will reload model's state_dict, optmizer's and schedulers's state_dicts, training state as well in a general case.
  use-case: to restart the training
  load_from_checkpoint just reloads the model's state_dict and return the model with the loaded weights.
  use-case: for quick evaluation/prediction.