code: def merge_heads(x):
      return merge_states(tf.transpose(a=x, perm=[0, 2, 1, 3]))
  
imports: import functools
  import numpy
  import tensorflow
  from finetune.optimizers.recompute_grads import recompute_grad
  from finetune.util.shapes import shape_list, lengths_from_eos_idx
  from finetune.nn.activations import act_fns
  from finetune.nn.nn_utils import dropout, norm
label_desc: Use image node_id 8 for calling a global function with example usage: merge_heads(x) and returns: merge_states