public function required($input, $key, $lang)
    {
        $lang = $this->custom('required', $lang);
        if (empty($input[$key])) {
            return str_replace(':field', $key, $lang);
        }
    }
public function required($input, $key, $lang)
    {
        $lang = $this->custom('required', $lang);
        if (empty($input[$key])) {
            return str_replace(':field', $key, $lang);
        }
    }
public function required ( $ input , $ key , $ lang ) { $ lang = $ this -> custom ( 'required' , $ lang ) ; if ( empty ( $ input [ $ key ] ) ) { return str_replace ( ':field' , $ key , $ lang ) ; } }
Parses a required validation field.

@param array  $input - Input to be validated
@param string $key   - Validation key
@param string $lang  - Language string

@return string
Parses a required validation field .