old_contents: 
  # import subpackages 
  from . import advection
  from . import cascade
  from . import io
  from . import noise
  from . import nowcasts
  from . import optflow
  from . import postprocessing
  from . import timeseries
  from . import utils
  from . import verification
  from . import visualization
  
  
  
new_contents: 
  # import subpackages 
  from . import advection
  from . import cascade
  from . import io
  from . import noise
  from . import nowcasts
  from . import optflow
  from . import postprocessing
  from . import timeseries
  from . import utils
  from . import verification as vf
  from . import visualization as plt
  
  
  
subject: Use namespaces plt and vf for visualization and verification modules