code: def get_func_name(self, hsh: bytes) -> str:
          
          if not isinstance(hsh, (bytes, bytearray)):
              raise TypeError('The selector argument must be a concrete byte array')
          sig = self._function_signatures_by_selector.get(hsh)
          return '{fallback}' if sig is None else sig[:sig.find('(')]
docs: Returns the name of the normal function with the selector ``hsh``,
          or ``'{fallback}'`` if no such function exists.