code: def L1(layer="input", constant=0):
      """L1 norm of layer. Generally used as penalty."""
      return lambda T: tf.reduce_sum(tf.abs(T(layer) - constant))
  
imports: from __future__ import absolute_import, division, print_function
  from decorator import decorator
  import numpy
  import tensorflow
  from lucid.optvis.objectives_util import _dot, _dot_cossim, _extract_act_pos, _make_arg_str, _T_force_NHWC, _T_handle_batch
label_desc: Use image node_id 10 for calling a global function with example usage: L1(layer, constant) and returns: function