anchor.diff:  get_output_format([{binary, true} | _])      -> binary;
   get_output_format([to_msg_defs | _])         -> msg_defs;
   get_output_format([{to_msg_defs, true} | _]) -> msg_defs;
  +get_output_format([nif | _])                 -> nif;
  +get_output_format([{nif, true} | _])         -> nif;
   get_output_format([_ | Rest])                -> get_output_format(Rest);
   get_output_format([])                        -> file.
   
  
positive.code: parse_opt({"I", [Dir]})          -> {true, {i,Dir}};
  parse_opt({"I"++Dir, []})        -> {true, {i,Dir}};
  parse_opt({"o", [Dir]})          -> {true, {o,Dir}};
  parse_opt({"v", ["optionally"]}) -> {true, {verify,optionally}};
  parse_opt({"v", ["always"]})     -> {true, {verify,always}};
  parse_opt({"v", ["never"]})      -> {true, {verify,never}};
  
negative.code:       "    -o Dir~n"
        "          Specify output directory for where to generate~n"
        "          the <Protofile>.erl and <Protofile>.hrl~n"
        "    -nif~n"
        "          Generate nifs for linking with the protobuf C(++) library.~n"
        "    -v optionally | always | never~n"
        "          Specify how the generated encoder should~n"
        "          verify the message to be encoded.~n"
  