How to use the pygmsh.generate_mesh function in pygmsh

def test(irad=0.05, orad=0.6):
    """Torus, rotated in space.
    """
    geom = pygmsh.built_in.Geometry()

    R = pygmsh.rotation_matrix([1.0, 0.0, 0.0], np.pi / 2)
    geom.add_torus(irad=irad, orad=orad, lcar=0.03, x0=[0.0, 0.0, -1.0], R=R)

    ref = 2 * np.pi ** 2 * orad * irad ** 2
    mesh = pygmsh.generate_mesh(geom)
    assert np.isclose(compute_volume(mesh), ref, rtol=5e-2)
    return mesh

def test():
    x = 5
    y = 4
    z = 3
    x_layers = 10
    y_layers = 5
    z_layers = 3
    geom = pygmsh.built_in.Geometry()
    p = geom.add_point([0, 0, 0], 1)
    _, l, _ = geom.extrude(p, [x, 0, 0], num_layers=x_layers)
    _, s, _ = geom.extrude(l, [0, y, 0], num_layers=y_layers)
    geom.extrude(s, [0, 0, z], num_layers=z_layers)
    mesh = pygmsh.generate_mesh(geom)

    ref_vol = x * y * z
    assert abs(compute_volume(mesh) - ref_vol) < 1.0e-2 * ref_vol

    # Each grid-cell from layered extrusion will result in 6 tetrahedrons.
    ref_tetras = 6 * x_layers * y_layers * z_layers
    assert len(mesh.cells_dict["tetra"]) == ref_tetras

    return mesh

def test(irad=0.05, orad=0.6):
    """Torus, rotated in space.
    """
    geom = pygmsh.built_in.Geometry()

    R = pygmsh.rotation_matrix([1.0, 0.0, 0.0], np.pi / 2)
    geom.add_torus(irad=irad, orad=orad, lcar=0.03, x0=[0.0, 0.0, -1.0], R=R)

    R = pygmsh.rotation_matrix([0.0, 1.0, 0.0], np.pi / 2)
    geom.add_torus(
        irad=irad, orad=orad, lcar=0.03, x0=[0.0, 0.0, 1.0], variant="extrude_circle"
    )

    ref = 2 * 2 * np.pi ** 2 * orad * irad ** 2
    mesh = pygmsh.generate_mesh(geom)
    assert np.isclose(compute_volume(mesh), ref, rtol=5e-2)
    return mesh

def test():
    x = 5
    y = 4
    z = 3
    x_layers = 10
    y_layers = 5
    z_layers = 3
    geom = pygmsh.opencascade.Geometry()
    p = geom.add_point([0, 0, 0], 1)
    _, l, _ = geom.extrude(p, [x, 0, 0], num_layers=x_layers)
    _, s, _ = geom.extrude(l, [0, y, 0], num_layers=y_layers)
    geom.extrude(s, [0, 0, z], num_layers=z_layers)
    mesh = pygmsh.generate_mesh(geom)

    ref_vol = x * y * z
    assert abs(compute_volume(mesh) - ref_vol) < 1.0e-2 * ref_vol

    # Each grid-cell from layered extrusion will result in 6 tetrahedrons.
    ref_tetras = 6 * x_layers * y_layers * z_layers
    assert len(mesh.cells_dict["tetra"]) == ref_tetras

    return mesh

def test():
    geom = pygmsh.opencascade.Geometry()

    geom.add_ellipsoid([1.0, 1.0, 1.0], [1.0, 2.0, 3.0], char_length=0.1)

    ref = 8.0 * pi
    mesh = pygmsh.generate_mesh(geom)
    assert abs(compute_volume(mesh) - ref) < 1.0e-2 * ref
    return mesh

def get_ball_mesh(k):
    import pygmsh

    h = 0.5 ** (k + 1)
    geom = pygmsh.built_in.Geometry()
    geom.add_ball([0.0, 0.0, 0.0], 1.0, lcar=h)
    mesh = pygmsh.generate_mesh(geom, verbose=False)
    cells = mesh.get_cells_type("tetra")
    # toss away unused points
    uvertices, uidx = numpy.unique(cells, return_inverse=True)
    cells = uidx.reshape(cells.shape)
    points = mesh.points[uvertices]
    return meshplex.MeshTetra(points, cells)

circle = geom.add_circle([0.5, 0.5, 0.0], 1.0, lcar)

    triangle = geom.add_polygon(
        [[2.0, -0.5, 0.0], [4.0, -0.5, 0.0], [4.0, 1.5, 0.0]], lcar
    )
    rectangle = geom.add_rectangle(4.75, 6.25, -0.24, 1.25, 0.0, lcar)

    # hold all domain
    geom.add_polygon(
        [[-1.0, -1.0, 0.0], [+7.0, -1.0, 0.0], [+7.0, +2.0, 0.0], [-1.0, +2.0, 0.0]],
        lcar,
        holes=[circle.line_loop, triangle.line_loop, rectangle.line_loop],
    )

    ref = 24.0
    mesh = pygmsh.generate_mesh(geom)
    assert abs(compute_volume(mesh) - ref) < 1.0e-2 * ref
    return mesh

_, rectangle, _ = geom.extrude(
        line, translation_axis=[0.0, lbw[1], 0.0], num_layers=lbw[1], recombine=True
    )
    geom.extrude(
        rectangle,
        translation_axis=[0.0, 0.0, lbw[2]],
        num_layers=lbw[2],
        recombine=True,
    )

    # compute_volume only supports 3D for tetras, but does return
    # surface area for quads

    ref = sum(l * w for l, w in permutations(lbw, 2))  # surface area
    mesh = pygmsh.generate_mesh(geom, prune_vertices=False)
    # TODO compute hex volumes
    assert (
        abs(
            compute_volume(meshio.Mesh(mesh.points, {"quad": mesh.cells_dict["quad"]}))
            - ref
        )
        < 1.0e-2 * ref
    )
    return mesh

[0.1, 0.1, 0.0],
        ],
        lcar=0.05,
    )

    axis = [0, 0, 1]

    geom.extrude(
        poly,
        translation_axis=axis,
        rotation_axis=axis,
        point_on_axis=[0, 0, 0],
        angle=2.0 / 6.0 * np.pi,
    )

    points, cells, _, _, _ = pg.generate_mesh(geom)
    return points, cells["tetra"]