question: Can custom logger extending `LightningLoggerBase` be imported from separate library?
context: I'm responsible for implementing pytorch_lightning.loggers.neptune.NeptuneLogger.
  Right now we're going through massive api update for neptune client, which requires updating NeptuneLogger in your repository (PyTorchLightning/pytorch-lightning).
  Theoretically we could implement our class NeptuneLogger(LightningLoggerBase) in our repo, and import this class as module in PyTorchLightning/pytorch-lightning.
  In such configuration we could easily update logger in our repo without having to create PR in PyTorchLightning/pytorch-lightning, when updating our api again in the future.
  Are there any reasons against such solution?
answer: Go for it! This is the best way to make sure users get the best experience.