You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: cnn_imagenet.m
    path of file: ./repos/cnn-for-image-retrieval/matconvnet-1.0-beta17/examples/imagenet
    
    the code of the file until where you have to start completion: function cnn_imagenet(varargin)
%CNN_IMAGENET   Demonstrates training a CNN on ImageNet
%  This demo demonstrates training the AlexNet, VGG-F, VGG-S, VGG-M,
%  VGG-VD-16, and VGG-VD-19 architectures on ImageNet data.

run(fullfile(fileparts(mf
    
function fn = getBatchFn(opts, meta)
% -------------------------------------------------------------------------
useGpu = numel(opts.train.gpus) > 0 ;

bopts.numThreads = opts.numFetchThreads ;
bopts.imageSize = meta.normalization.imageSize ;
bopts.border = meta.normalization.border ;
bopts.averageImage = meta.normalization.averageImage ;
bopts.rgbVariance = meta.augmentation.rgbVariance ;
bopts.transformation = meta.augmentation.transformation ;

switch lower(opts.networkType)
  case 'simplenn'
    fn = @(x,y) getSimpleNNBatch(bopts,x,y) ;
  case 'dagnn'
    fn = @(x,y) getDagNNBatch(bopts,useGpu,x,y) ;
end