checkValidPanNumber static method
Check if string is a valid PAN number (Indian PAN format)
panNumber - The PAN number to validate
Returns true if PAN number is valid
Implementation
static bool checkValidPanNumber(String panNumber) {
// PAN format: 5 letters, 4 digits, 1 letter (e.g., ABCDE1234F)
final panRegex = RegExp(r'^[A-Z]{5}[0-9]{4}[A-Z]{1}$');
return panRegex.hasMatch(panNumber.toUpperCase());
}