Golang中的EnumChildWindows回调函数

Using package lxn/win in main:

win.EnumChildWindows(hw, printme, 0)

Then after main:

func printme(HWND win.HANDLE, LPARAM uintptr) { //HWND hwnd, LPARAM lParam
    spew.Dump(HWND)
}

I get:

.\test.go:40: cannot use printme (type func(win.HANDLE, uintptr)) as type uintptr in argument to win.EnumChildWindows

error:exit status 2

I don't understand the error message.