keras/src/applications/mobilenet_v3.py/preprocess_input
def preprocess_input(x, data_format=None):
    """A placeholder method for backward compatibility.

    The preprocessing logic has been included in the mobilenet_v3 model
    implementation. Users are no longer required to call this method to
    normalize the input data. This method does nothing and only kept as a
    placeholder to align the API surface between old and new version of model.

    Args:
        x: A floating point `numpy.array` or a tensor.
        data_format: Optional data format of the image tensor/array.
            `None` means the global setting
            `keras.config.image_data_format()` is used
            (unless you changed it, it uses `"channels_last"`).
            Defaults to `None`.

    Returns:
        Unchanged `numpy.array` or tensor.
    """
    return x