run method
Run pub run on the given package and script.
If script is null it defaults to the same value as package.
Implementation
static String run(String package,
{List<String> arguments,
RunOptions runOptions,
String script,
String workingDirectory}) {
runOptions = mergeWorkingDirectory(workingDirectory, runOptions);
var scriptArg = script == null ? package : '$package:$script';
List<String> args = ['run', scriptArg];
if (arguments != null) args.addAll(arguments);
return runlib.run(sdkBin('pub'), arguments: args, runOptions: runOptions);
}