isBase58 function
Checks if the string is base58 encoded.
Base58 encoding is a binary-to-text encoding used to represent large integers as alphanumeric text. It uses a 58-character subset of ASCII excluding the similar-looking characters: 0 (zero), O (capital o), I (capital i), and l (lowercase L).
Returns true if the string is valid base58 encoded, otherwise returns false.
Example:
isBase58('3yDKLZJ4PC1HE4Y8L8Esx'); // true
isBase58('hello 0OIl world'); // false
Implementation
bool isBase58(String str) => _isBase58(str);