FactoryFuncParam<T, P1, P2> typedef
FactoryFuncParam<T, P1, P2> =
T Function(P1 param1, P2 param2)
For Factories that expect up to two parameters if you need only one use void
for the one
you don't use
Implementation
typedef FactoryFuncParam<T, P1, P2> = T Function(
P1 param1,
P2 param2,
);