framework/i18n/Formatter.php
public function asBoolean($value)
    {
        if ($value === null) {
            return $this->nullDisplay;
        }

        return $value ? $this->booleanFormat[1] : $this->booleanFormat[0];
    }
public function asBoolean($value)
    {
        if ($value === null) {
            return $this->nullDisplay;
        }

        return $value ? $this->booleanFormat[1] : $this->booleanFormat[0];
    }
Formats the value as a boolean.
@param mixed $value the value to be formatted.
@return string the formatted result.
@see booleanFormat