set result := NFA.done.pushRegex ⟨0, by decide⟩ r
r : Data.Expr
nfa : NFA
eq : ↑(done.pushRegex ⟨0, compile.proof_1⟩ r) = nfa
⊢ 0 < nfa.nodes.size
r : Data.Expr
nfa : NFA
result : { nfa' // done.nodes.size < nfa'.nodes.size } := done.pushRegex ⟨0, ⋯⟩ r
eq : ↑result = nfa
⊢ 0 < nfa.nodes.size