code: func (e *Encoding) DecodeToInt64(s string) int64 {
  	var (
  		n     int64
  		c     int64
  		idx   int
  		power int
  	)
  
  	for i, v := range s {
  		idx = strings.IndexRune(e.encode, v)
  
  		// Work downwards through powers of our base
  		power = len(s) - (i + 1)
  
  		// Calculate value at this position and add
  		c = int64(idx) * int64(math.Pow(float64(base), float64(power)))
  		n = n + c
  	}
  
  	return int64(n)
  }
docs: // DecodeToInt64 decodes a base62 encoded string