let help =
"Submit proof obligations to external prover:\n- 'none' to skip proofs\nDirectly supported provers:\n- 'alt-ergo' (default)\n- 'coq', 'coqide' (see also -wp-script)\nSupported provers via Why:\n- 'simplify', 'vampire', 'yices', 'cvc3', 'z3', 'zenon'"