function Option.Expect(R,a)assert(R:IsSome(),a)return R._v end
--[=[
	@param msg string
	@return value: any
	Unwraps the value in the option, otherwise throws an error with `msg` as the error message.
	```lua
	local opt = Option.Some(10)
	print(opt:Expect("No number")) -> 10
	print(Option.None:Expect("No number")) -- Throws an error "No number"
	```
]=]
function Option:Expect(msg)
	assert(self:IsSome(), msg)
	return self._v
end
