Function4<A, B, C, D, R>  typedef 
 
        Function4<A, B, C, D, R> =
     R Function(A a, B b, C c, D d)
     
    
    
Implementation
typedef Function4<A, B, C, D, R> = R Function(A a, B b, C c, D d);typedef Function4<A, B, C, D, R> = R Function(A a, B b, C c, D d);