keras/src/ops/math.py/STFT/compute_output_spec
class STFT:    def compute_output_spec(self, x):
        if x.shape[-1] is not None:
            padded = 0 if self.center is False else (self.fft_length // 2) * 2
            num_sequences = (
                1
                + (x.shape[-1] + padded - self.fft_length)
                // self.sequence_stride
            )
        else:
            num_sequences = None
        new_shape = x.shape[:-1] + (num_sequences, self.fft_length // 2 + 1)
        return (
            KerasTensor(shape=new_shape, dtype=x.dtype),
            KerasTensor(shape=new_shape, dtype=x.dtype),
        )