code: def convert_flatten(net, node, module, builder):
      
      input_name, output_name = _get_input_output_name(net, node)
      name = node['name']
      mode = 0 # CHANNEL_FIRST
      builder.add_flatten(name, mode, input_name, output_name)
docs: Convert a flatten layer from mxnet to coreml.
  
      Parameters
      ----------
      network: net
          A mxnet network object.
  
      layer: node
          Node to convert.
  
      module: module
          An module for MXNet
  
      builder: NeuralNetworkBuilder
          A neural network builder object.