How to use the jake.task function in jake

ApplicationTask.prototype.defineCacheManifestTask = function()
{
    if (!this.shouldGenerateCacheManifest())
        return;

    var productPath = FILE.join(this.buildProductPath(), "");
    var indexFilePath = this.buildIndexFilePath();

    // TODO: can we conditionally generate based on outdated files?
    var manifestPath = FILE.join(productPath, "app.manifest");
    Jake.task(manifestPath, function() {
        require("../cache-manifest").generateManifest(productPath, { index : indexFilePath });
    });

    this.enhance([manifestPath]);
}

catch(error)
		{
			print("Build Task Failed : " + error.message);
			OS.exit(1);
		}
		finally
		{
			//cleanup here?
		}
	
		print("Build Task Complete");
	}
);


task("build-docs", [],
	function()
	{
		if(system.args < 3)
		{
			print("USAGE : jake build-docs build_version");
			OS.exit(1);
		}		
		
		var version = system.args[2];
		
		if(!version)
		{
			print("USAGE : jake build-docs build_version");
			OS.exit(1);	
		}

"../src/easeljs/display/Container.js",
	"../src/easeljs/display/Stage.js",
	"../src/easeljs/display/Bitmap.js",
	"../src/easeljs/display/BitmapSequence.js",
	"../src/easeljs/display/Shape.js",
	"../src/easeljs/display/Text.js",
	"../src/easeljs/utils/SpriteSheetUtils.js",
	"../src/easeljs/display/DOMElement.js",
	"../src/easeljs/filters/Filter.js",
	"../src/easeljs/filters/BoxBlurFilter.js",
	"../src/easeljs/filters/ColorFilter.js",
	"../src/easeljs/filters/ColorMatrixFilter.js",
	"../src/easeljs/ui/Touch.js"
];

task("default", ["build", "build-docs"],
	function()
	{
		print("Build Complete : " + system.args);
	}
);

task("build", [],
	function()
	{
		var output_dir = "output";
		
		if(!FILE.exists(output_dir))
		{
			//do we need to make sure this is relative to the build directory?
			FILE.mkdir(output_dir);
		}

"../src/easeljs/display/DOMElement.js",
	"../src/easeljs/filters/Filter.js",
	"../src/easeljs/filters/BoxBlurFilter.js",
	"../src/easeljs/filters/ColorFilter.js",
	"../src/easeljs/filters/ColorMatrixFilter.js",
	"../src/easeljs/ui/Touch.js"
];

task("default", ["build", "build-docs"],
	function()
	{
		print("Build Complete : " + system.args);
	}
);

task("build", [],
	function()
	{
		var output_dir = "output";
		
		if(!FILE.exists(output_dir))
		{
			//do we need to make sure this is relative to the build directory?
			FILE.mkdir(output_dir);
		}
		
		//catch errors and fail, cleanup and fail gracefully
		//test with paths that contain spaces
		
		try
		{
			var file_args = [];