old_contents: from .scatter import scatter
  from .velocity import velocity
  from .velocity_embedding import velocity_embedding
  from .velocity_embedding_grid import velocity_embedding_grid
  
new_contents: from .scatter import scatter
  from .velocity import velocity
  from .velocity_embedding import velocity_embedding
  from .velocity_embedding_grid import velocity_embedding_grid
  from .utils import hist
  
subject: add scv.pl.hist