code: def l1(x):
      """Computes the L1 norm of a tensor
  
      Parameters
      ----------
      x : Theano tensor
  
      Returns
      -------
      Theano scalar
          l1 norm (sum of absolute values of elements)
      """
      return T.sum(abs(x))
  
file_path: Lasagne/lasagne/regularization.py
imports: import theano.tensor
  from .layers import Layer, get_all_params
label_desc: Use image node_id 1 for calling a global function with example usage: l1(x) and returns: T