[Python] AttributeError: module 'dolfinx.fem' has no attribute 'LinearProblem'

I'm new to DOLFINx and I'm trying to run this script.

import numpy as np
from mpi4py import MPI
import dolfinx
import ufl
import pyvista
from petsc4py import PETSc

print("version", dolfinx.__version__)
print("file", dolfinx.__file__)


domain = dolfinx.mesh.create_unit_square(MPI.COMM_WORLD, 10, 10)

V = dolfinx.fem.functionspace(domain, ("CG", 1))


u_bc = dolfinx.fem.Function(V)
u_bc.x.array[:] = 0.0

def boundary(x):
return np.full(x.shape[1], True)

bc = dolfinx.fem.dirichletbc(u_bc, dolfinx.fem.locate_dofs_geometrical(V, boundary))


u = ufl.TrialFunction(V)
v = ufl.TestFunction(V)
f = dolfinx.fem.Constant(domain, 1.0) # RHS = 1

a = ufl.dot(ufl.grad(u), ufl.grad(v)) * ufl.dx
L = f * v * ufl.dx

a = dolfinx.fem.form(a)
L = dolfinx.fem.form(L)

problem = dolfinx.fem.LinearProblem(a, L, bcs=[bc], petsc_options={"ksp_type": "cg", "pc_type": "hypre"})
uh = problem.solve()



I am not aware that they renamed or moved LinearProblem. I am using version 0.10.0 of dolfinx:stable.

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