StringToByteFunc.go

out := ethutil.StringToByteFunc(str, func(s string) (ret []byte) {
	ret = doSomethingWith(s)
	return
})

// ==

var out []byte
if s[0:2] == "0x" {
	out = fromHex([2:])
} else {
	out = doSomethingWith(s)
}