old_contents: from .grassmann import Grassmann
  from .sphere import Sphere
  from .stiefel import Stiefel
  from .psd import PSDFixedRank, PSDFixedRankComplex, Elliptope, PositiveDefinite
  from .oblique import Oblique
  from .euclidean import Euclidean, Symmetric
  from .product import Product
  
  __all__ = ["Grassmann", "Sphere", "Stiefel", "PSDFixedRank",
             "PSDFixedRankComplex", "Elliptope", "PositiveDefinite", "Oblique",
             "Euclidean", "Product", "Symmetric"]
  
new_contents: from .grassmann import Grassmann
  from .sphere import Sphere
  from .stiefel import Stiefel
  from .psd import PSDFixedRank, PSDFixedRankComplex, Elliptope, PositiveDefinite
  from .oblique import Oblique
  from .euclidean import Euclidean, Symmetric
  from .product import Product
  from .fixed_rank import FixedRankEmbedded
  
  __all__ = ["Grassmann", "Sphere", "Stiefel", "PSDFixedRank",
             "PSDFixedRankComplex", "Elliptope", "PositiveDefinite", "Oblique",
             "Euclidean", "Product", "Symmetric", "FixedRankEmbedded"]
  
subject: Add FixedRankEmbedded to manifolds init.