def fill_in(self, tensor_dict):
        """Maps KerasTensors to computed values using `tensor_dict`.

        `tensor_dict` maps `KerasTensor` instances to their current values.
        """
        if self._single_positional_tensor is not None:
            # Performance optimization for most common case.
            # Approx. 70x faster.
            return (tensor_dict[id(self._single_positional_tensor)],), {}

        def switch_fn(x):
            if isinstance(x, KerasTensor):
                return tensor_dict.get(id(x), None)
            return x

        return self.convert(switch_fn)
Maps KerasTensors to computed values using `tensor_dict`.

        `tensor_dict` maps `KerasTensor` instances to their current values.
        
keras/src/ops/symbolic_arguments.py