How to implement problem with only Neumann BCs, no Dirichlet

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I’m trying to solve a problem which only has Neumann conditions at the boundary, which are \frac{dN}{dn}=0 on the entire boundary {\partial \Omega} of my domain. These are encompassed in my variational formulation, as I end up with a \int_{\partial\Omega} v \frac{dN}{dn} {\partial S} term which is equal to zero. I have no Dirichlet boundary conditions.

The nonlinear solver I am trying to use requires the boundary conditions to be stated explicitly, as bc in problem = fem.petsc.NonlinearProblem(F, N, bcs=[bc]) . I can’t find a tutorial which doesn’t have Dirichlet boundary conditions, so I’m not sure how to implement this. Could anyone provide any advice?

I’ve not included a MWE because this is more of a general how-to-proceed question, but I can do if it’s helpful. Thanks in advance!

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Simply send in an empty list bcs=[]
or not send in any argument, i.e. fem.petsc.NonlinearProblem(F, N) as it has a default value:

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