package Base;
    
    multimethod new => (Value_eq('Base'))           => sub {...}    
    multimethod new => (Value_eq('Base'), Negative) => sub {...}
    multimethod new => (Value_eq('Base'), '#')      => sub {...}
    
    package Der;
    use base 'Base';
    
    multimethod new => (Value_eq('Der'))      => sub {...}  
    multimethod new => (Value_eq('Der'), '$') => sub {...}  
    # etc.