code: def _get_bounds_local(layers):
      
      if not layers:
          return {'west': None, 'south': None, 'east': None, 'north': None}
  
      bounds = layers[0].bounds
  
      for layer in layers[1:]:
          bounds = np.concatenate(
              (
                  np.minimum(
                      bounds[:2],
                      layer.bounds[:2]
                  ),
                  np.maximum(
                      bounds[2:],
                      layer.bounds[2:]
                  )
              )
          )
  
      return dict(zip(['west', 'south', 'east', 'north'], bounds))
docs: Aggregates bounding boxes of all local layers
  
          return: dict of bounding box of all bounds in layers