# filename method

String filename(

1. String image,
2. String? tag

)

Formate image and tag to filename format

## Implementation

    String filename(String image, String? tag) {
      if (image.isEmpty) {
        throw Exception('Image is not valid');
      }
      final filename = image.replaceAll(RegExp(r'[^a-zA-Z0-9]'), '_');
      if (tag == null) {
        return filename;
      }
      final tagFilename = tag.replaceAll(RegExp(r'[^a-zA-Z0-9]'), '_');
      return '${filename}_$tagFilename';
    }