anchor.diff:    --compile-sdk=<patched_sdk>
       Compile the SDK from scratch instead of reading it from 'platform.dill'.
   
  +  --sdk=<patched_sdk>
  +    Location of the SDK sources for use when compiling additional platform
  +    libraries.
  +
     --fatal=errors
     --fatal=warnings
     --fatal=nits
  
positive.code:   "--compile-sdk": Uri,
    "--fatal": ",",
    "--output": Uri,
    "--packages": Uri,
    "--platform": Uri,
    "-o": Uri,
    "--target": String,
    "-t": String,
  };
  
negative.code:     }
      if (options.containsKey("-t") && options.containsKey("--target")) {
        return argumentError(usage, "Can't specify both '-t' and '--target'.");
      }
      if (options.containsKey("--compile-sdk") &&
          options.containsKey("--platform")) {
        return argumentError(
            usage, "Can't specify both '--compile-sdk' and '--platform'.");
      }
      if (programName == "compile_platform" && arguments.length != 3) {
        return argumentError(usage, "Expected three arguments.");
  