code: def U(self):
          
          u = self.call("U")
          if u is not None:
              mat_name = u.getClass().getSimpleName()
              if mat_name == "RowMatrix":
                  return RowMatrix(u)
              elif mat_name == "IndexedRowMatrix":
                  return IndexedRowMatrix(u)
              else:
                  raise TypeError("Expected RowMatrix/IndexedRowMatrix got %s" % mat_name)
docs: Returns a distributed matrix whose columns are the left
          singular vectors of the SingularValueDecomposition if computeU was set to be True.