public function get($key = null, $default = null, $nullIfEmpty = false) {
        return InternalHelper::getSingleKeyOrAll($this->get, $key, $default, $nullIfEmpty);
    }
public function get($key = null, $default = null, $nullIfEmpty = false) {
        return InternalHelper::getSingleKeyOrAll($this->get, $key, $default, $nullIfEmpty);
    }
public function get ( $ key = null , $ default = null , $ nullIfEmpty = false ) { return InternalHelper :: getSingleKeyOrAll ( $ this -> get , $ key , $ default , $ nullIfEmpty ) ; }
Returns GET data.

@param string|null $key The key to get. Default: null - all keys.
@param string|null $default The default value if the key is not null, and the value with the specified key was not found. The default value is null.
@param bool $nullIfEmpty Check the value with the empty() function. If empty() returns true, the function returns $default.

@return array|mixed
Returns GET data .