def _get_output(layer, index=0):
    """
    :param layer : NN Layer Proto message
    :param index : Layer output index (Default 0)
    :returns name of output at provided index if present, otherwise None
    """
    if len(layer.output) <= index:
        return None
    return layer.output[index]

    :param layer : NN Layer Proto message
    :param index : Layer output index (Default 0)
    :returns name of output at provided index if present, otherwise None
    
coremltools/converters/mil/backend/nn/passes/mlmodel_passes.py