CakeRequest::param PHP Method

    public function param($name)
    {
        $args = func_get_args();
        if (count($args) === 2) {
            $this->params = Hash::insert($this->params, $name, $args[1]);
            return $this;
        }
        if (!isset($this->params[$name])) {
            return Hash::get($this->params, $name, false);
        }
        return $this->params[$name];
    }

 /**
  * test writing request params with param()
  *
  * @return void
  */
 public function testParamWriting()
 {
     $request = new CakeRequest('/');
     $request->addParams(array('action' => 'index'));
     $this->assertInstanceOf('CakeRequest', $request->param('some', 'thing'), 'Method has not returned $this');
     $request->param('Post.null', null);
     $this->assertNull($request->params['Post']['null']);
     $request->param('Post.false', false);
     $this->assertFalse($request->params['Post']['false']);
     $request->param('Post.zero', 0);
     $this->assertSame(0, $request->params['Post']['zero']);
     $request->param('Post.empty', '');
     $this->assertSame('', $request->params['Post']['empty']);
     $this->assertSame('index', $request->action);
     $request->param('action', 'edit');
     $this->assertSame('edit', $request->action);
 }