how can i apply newmann boundary conditions in both sides ?

[liucuixi]

the equation is the same formation as heat equation in demos, however it has to newmann boundary conditions , the codes are

def boundary_r(x, on_boundary):
return on_boundary and dde.utils.isclose(x[0], 0)
def boundary_l(x, on_boundary):
return on_boundary and dde.utils.isclose(x[0], L)

bc_r = dde.icbc.NeumannBC(geom, lambda X: -bc, boundary_r)
bc_l = dde.icbc.NeumannBC(geom, lambda X: bc, boundary_l)

c = dde.icbc.IC(.....)
and i was stucked by the following code