code: def linear(x):
      """Linear activation function :math:`\\varphi(x) = x`
  
      Parameters
      ----------
      x : float32
          The activation (the summed, weighted input of a neuron).
  
      Returns
      -------
      float32
          The output of the identity applied to the activation.
      """
      return x
  
file_path: Lasagne/lasagne/nonlinearities.py
imports: import theano.tensor
label_desc: Use image node_id 7 for calling a global function with example usage: linear(x) and returns: x