anchor.diff:    "--compile-sdk": Uri,
     "--fatal": ",",
     "--output": Uri,
  +  "-o": Uri,
     "--packages": Uri,
     "--platform": Uri,
  -  "-o": Uri,
  +  "--sdk": Uri,
     "--target": String,
     "-t": String,
   };
  
positive.code:     }
      if (options.containsKey("-t") && options.containsKey("--target")) {
        return argumentError(usage, "Can't specify both '-t' and '--target'.");
      }
      if (programName == "compile_platform" && arguments.length != 3) {
        return argumentError(usage, "Expected three arguments.");
  
negative.code: 
    Uri get packages => options["--packages"] ?? Uri.base.resolve(".packages");
  
    Uri get sdk => options["--sdk"] ?? options["--compile-sdk"];
  
    Set<String> get fatal {
      return new Set<String>.from(options["--fatal"] ?? <String>[]);
  