code: def layer_outdim3(self):
      from lasagne.layers.shape import FlattenLayer
  
      return FlattenLayer(Mock(output_shape=(None,)), outdim=3)
  
imports: import numpy
  import pytest
  import theano
  from mock import Mock
label_desc: Use image node_id 2 for calling the TestFlattenLayer obj's underlying member method code with example usage: obj.layer_outdim3() and returns: FlattenLayer