code: def face_angles_sparse(mesh):
      
      matrix = coo_matrix((mesh.face_angles.flatten(),
                           (mesh.faces_sparse.row, mesh.faces_sparse.col)),
                          mesh.faces_sparse.shape)
      return matrix
docs: A sparse matrix representation of the face angles.
  
      Returns
      ----------
      sparse: scipy.sparse.coo_matrix with:
              dtype: float
              shape: (len(mesh.vertices), len(mesh.faces))