old_contents: from .base import ATM, PatchBasedATM
  from .builder import ATMBuilder, PatchBasedATMBuilder
  from .fitter import LucasKanadeATMFitter
  
new_contents: from .builder import (
      ATMBuilder, PatchATMBuilder, LinearATMBuilder,
      LinearPatchATMBuilder, PartsATMBuilder)
  from .fitter import LKATMFitter
  from .algorithm import FC, IC
subject: Add __init__.py for ATMs