code: func IsRsaPub(str string, params ...string) bool {
  	if len(params) == 1 {
  		len, _ := ToInt(params[0])
  		return IsRsaPublicKey(str, int(len))
  	}
  
  	return false
  }
docs: // IsRsaPub check whether string is valid RSA key
  // Alias for IsRsaPublicKey