Thunno 2 v, 6 bytes
ıʠ€ạ;ạ Explanation
ıʠ€ạ;ạ # Implicit input ı ; # Map: ʠ # Powerset of the string € # For each one: ạ # Check if all equal ạ # Check if all equal # Implicit output v, 6 bytesıʠ€ạ;ạ ıʠ€ạ;ạ # Implicit input ı ; # Map: ʠ # Powerset of the string € # For each one: ạ # Check if all equal ạ # Check if all equal # Implicit output