### What problem does this PR solve?
feat: change all file names to lowercase #1574
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
feat: modify the style of the operator #918
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
feat: modify the name of an operator #918
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
feat: restrict classification operators cannot be connected to Answer
and other classification #918
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
