suggest to make 'createEvents' type friendley

[Yuddomack]

I was trying to create a custom event for experiment (like this #949)
but did some mistakes because the type was not clear little.

I didn't want to someother make same mistake,
Help them see for themselves what they are doing.

so I added a type specification to help with type inference.

It make improve type inference

before (any)	after (inferred)

+ Additionally

multiple parameter passing is possible by this

call(...arg) {
  handlers.forEach((fn) => fn && fn(...arg));
}

before	after

if you don't think need multi parameter, can change like this

• EventType

type Events<F extends EventHandler> = {
  length: number;
  push: (fn: F) => () => void;
  call: (arg: Parameters<F>[0]) => void; // can change optional if need
};

• Events.call

// ...
call(arg) {
  handlers.forEach((fn) => fn && fn(arg));
},
// ...

Thank you

Please consider to this pull request!
and Thank you for providing a good ecosystem!