src/Option.php
public function isa($type, $option = null)
    {
        // "bool" was kept for backward compatibility
        if ($type === 'bool') {
            $type = 'boolean';
        }
        $this->isa = $type;
        $this->isaOption = $option;

        return $this;
    }
public function isa($type, $option = null)
    {
        // "bool" was kept for backward compatibility
        if ($type === 'bool') {
            $type = 'boolean';
        }
        $this->isa = $type;
        $this->isaOption = $option;

        return $this;
    }
Value Type Setters.

@param string $type   the value type, valid values are 'number', 'string',
'file', 'boolean', you can also use your own value type name.
@param mixed  $option option(s) for value type class (optionnal)