validateConfigFileName function
Validates that the given fileName is alphanumeric (with underscores as spaces) and does not start with a number.
Implementation
bool validateConfigFileName(String fileName) {
final alphabets = RegExp(r'^[a-zA-Z_]+$');
final alphaNumeric = RegExp(r'^[a-zA-Z0-9_]+$');
return alphabets.hasMatch(fileName[0]) &&
alphaNumeric.hasMatch(fileName.substring(1));
}