openScoped.lean:1:7-1:14: error: unknown identifier 'epsilon'
openScoped.lean:4:2-4:24: error: failed to synthesize
  Decidable (f = g)
Additional diagnostic information may be available using the `set_option diagnostics true` command.
Classical.epsilon.{u} {α : Sort u} [h : Nonempty α] (p : α → Prop) : α
openScoped.lean:15:7-15:14: error: unknown identifier 'epsilon'
openScoped.lean:20:7-20:14: error: unknown identifier 'epsilon'