src/Radio.php
public function isRequired() : Testable
    {
        $this->attributes['required'] = true;
        return $this->addTest('required', function($value) {
            return $this->checked();
        });
    }
public function isRequired() : Testable
    {
        $this->attributes['required'] = true;
        return $this->addTest('required', function($value) {
            return $this->checked();
        });
    }
public function isRequired ( ) : Testable { $ this -> attributes [ 'required' ] = true ; return $ this -> addTest ( 'required' , function ( $ value ) { return $ this -> checked ( ) ; } ) ; }
Mark the field as required.

@return self
Mark the field as required .