import tensorflow as tf

    * masks: list of masks for weight sparsification
    * prune_op: pruning operation
    """

    masks, prune_ops = [], []
    with tf.variable_scope(self.mask_scope):
      for var, var_name_n_prune_ratio in zip(self.maskable_vars, self.var_names_n_prune_ratios):
        # obtain the dynamic pruning ratio
        assert var.name == var_name_n_prune_ratio[0], \
          'unmatched variable names: %s vs. %s' % (var.name, var_name_n_prune_ratio[0])
