simp
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
x : Node
xs : List Node
⊢ {y | ∃ x_1 ∈ x :: xs, y ∈ direct_succ_list g x_1} =
    ↑(direct_succ_list g x).toFinset ∪ {y | ∃ x ∈ xs, y ∈ direct_succ_list g x}
Node : Type
inst✝ : DecidableEq Node
g : Graph Node
x : Node
xs : List Node
⊢ {y | y ∈ direct_succ_list g x ∨ ∃ a ∈ xs, y ∈ direct_succ_list g a} =
    {a | a ∈ direct_succ_list g x} ∪ {y | ∃ x ∈ xs, y ∈ direct_succ_list g x}