set group option, it is different of withGroup, the latter return new instance
@param string $key
@return static
344131
public function setGroup($group)
    {
        if (isset($this->options['group']) && $this->options['group']) {
            $group = $this->options['group'] . '/' . $group;
        }
        return $this->setOption('group', $group);
    }
302473
static function &getInstance($key=null)
	{
		static $instances;

		if (!isset($instances))
		{
			$instances = array();
		}

		if (!isset($instances[$key]))
		{
			$instances[$key] = new static($key);
		}

		return $instances[$key];
	}
904483
public function remove($key)
    {
        if ($this->isAcceptable($key)) {
            $key = $this->modelKey($key);
        }

        unset($this->objects[$key]);

        return $this;
    }
489222
public function setDevKey($key)
    {
        $this->validator->validateDeveloperKey($key);

        $this->devKey = $key;

        return $this;
    }
673930
public function setOption($key, $value)
    {

        $this->getTargetConfigurableObject()
            ->setOption($this->getOptionName($key), $value);

        return $this;
    }
297076
public static function setOption($key, $val)
    {
        self::init();
        return self::$instance->setOption($key, $val);
    }
800533
public static function instance(string $key)
    {
        $collection = static::make();

        $class = $collection->get($key);

        if (class_exists($class)) {
            return resolve($class);
        }

        return null;
    }
545293
public function setGroup($group)
    {
        $this->fieldName = null;

        $group = str_replace('.', '/', $group);

        $this->group = $group;

        return $this;
    }
147979
public function key($key = null) {
		if($key === null) return $this->key;
		$this->key = $key;
		return $this;
	}
1192825
public function setGroup($group)
    {
        $this->group = $group instanceof SID ? $group : new SID($group);

        return $this;
    }
277413
public function remove($key) {
        if (isset($this->_attrs[$key])) {
            unset($this->_attrs[$key]);
        }
        
        return $this;
    }
1246891
public function remove($key)
    {
        if (isset($this->fields[$key])) {
            unset($this->fields[$key]);
        }
        return $this;
    }
1240837
static function groups($key = null)
    {
        if (!isset(self::$trace)) self::$trace = new Trace('TRACE');
        if (isset($key)){
            return self::$trace->__get($key);
        }else{
            return self::$trace;
        }
    }
718921
public function remove(string $key): self
    {
        if (isset($this->headers[$key]) == true) {
            unset($this->headers[$key]);
        }

        return $this;
    }
977460
public function column($key)
    {
        $result = array_column($this->all(), $key);

        if (empty($result)) {
            $this->each(function ($item) use (&$result, $key) {
                array_push($result, $item->{$key});
            });
        }

        return new static($result);
    }
844512
public function add($key)
    {
        $configuration = new AdminConfigurationGroup();

        $configuration->key($key);
        $this->configurations->put($key, $configuration);

        return $configuration;
    }
182089
public function setGroup($group)
    {
        if (!empty($group)) {
            $this->query['group'] = $group;
        } else {
            unset($this->query['group']);
        }
        return $this;
    }