Need help with fetching word from a string.

I have tried with following regex

package main

import (
    "fmt"
    "regexp"
)

func main() {
    var re = regexp.MustCompile(`s+(?:w+_w+)`)
    var str = `func1(A)`

    for i, match := range re.FindAllString(str, -1) {
        fmt.Println(match, "found at index", i)
    }
}

But this returning not any word incase there’s no space eg: for string “func1(A)”. This is working as expected when the word has a space before. Any help would be appreciated