func next_pattern_instruction(p string) (byte, byte) {
    ch := p[0]
    var pt byte = 1
    if len(p) > 1 && p[1] == '*' {
        pt = '*'
    }

    return ch, pt
}

func isMatch(s string, p string) bool {
    if len(p) == 0 {
        return len(s) == 0
    }

    ch, pt := next_pattern_instruction(p)

    if pt == 1 {
        // (1) a, 1 - s[0] == ch
        // (3) ., 1 - len(s) >= 1
        return len(s) >= 1 && (ch == '.' || s[0] == ch) && isMatch(s[1:], p[1:])
    } else {
        // (2) a, * - s[0] == ch || len(s) == 0
        // (4) ., * - len(s) >= 0

        // the pattern can happen 0 times regardless if there are characters or not
        if isMatch(s, p[2:]) {
            return true
        }
        // if there are characters we will try consuming them
        if len(s) >= 1 && (ch == '.' || s[0] == ch) {
            if isMatch(s[1:], p[2:]) {
                return true
            }
            return isMatch(s[1:], p)
        }
        return false
    }
}