code: def fprop(self, x):
      w, b = self.make_vars()
      return tf.nn.xw_plus_b(x, w, b)
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import numpy
  import tensorflow
  from cleverhans.serial import NoRefModel
label_desc: Use image node_id 4 for calling the Linear obj's underlying member method code with example usage: obj.fprop(x) and returns: tf