keras/src/layers/preprocessing/index_lookup.py/IndexLookup/compute_output_shape
class IndexLookup:    def compute_output_shape(self, input_shape):
        if self.output_mode == "int":
            return input_shape
        depth = (
            self.max_tokens
            if self.pad_to_max_tokens
            else self._frozen_vocab_size
        )
        return (input_shape[0], depth)