code: def uniform(obj):
      
      from .spaces import HoloMap
      dim_groups = obj.traverse(lambda x: tuple(x.kdims),
                                (HoloMap,))
      if dim_groups:
          dgroups = [frozenset(d.name for d in dg) for dg in dim_groups]
          return all(g1 <= g2 or g1 >= g2 for g1 in dgroups for g2 in dgroups)
      return True
docs: Finds all common dimension keys in the object including subsets of
      dimensions. If there are is no common subset of dimensions, None
      is returned.