code: func (ns *Namespace) Mod(a, b interface{}) (int64, error) {
  	ai, erra := cast.ToInt64E(a)
  	bi, errb := cast.ToInt64E(b)
  
  	if erra != nil || errb != nil {
  		return 0, errors.New("modulo operator can't be used with non integer value")
  	}
  
  	if bi == 0 {
  		return 0, errors.New("the number can't be divided by zero at modulo operation")
  	}
  
  	return ai % bi, nil
  }
docs: // Mod returns a % b.