if n == 0 {
    return nil
}
if sep == "" {
    return explode(s, n)
}
if n < 0 {
    n = strings.Count(s, sep) + 1
}
c := sep[0]
start := 0
a := make([]string, n)
na := 0
if len(sep)==1 {
    for i := 0; i < len(s) && na+1 < n; i++ {
        if s[i] == c {
            a[na] = s[start : i+sepSave]
                na++
                start = i + 1
            }
        }
} else {
    for i := 0; i+len(sep) <= len(s) && na+1 < n; i++ {
        if s[i] == c && s[i:i+len(sep)] == sep {
            a[na] = s[start : i+sepSave]
            na++
            start = i + len(sep)
            i += len(sep) - 1
        }
    }
}
a[na] = s[start:]
return a[0 : na+1]