keras/src/layers/reshaping/cropping1d.py/Cropping1D/compute_output_shape
class Cropping1D:    def compute_output_shape(self, input_shape):
        if input_shape[1] is not None:
            length = input_shape[1] - self.cropping[0] - self.cropping[1]
            if length <= 0:
                raise ValueError(
                    "`cropping` parameter of `Cropping1D` layer must be "
                    "smaller than the input length. Received: input_shape="
                    f"{input_shape}, cropping={self.cropping}"
                )
        else:
            length = None
        return (input_shape[0], length, input_shape[2])