code: def concatenate_unique(la, lb):
      """Add all the elements of `lb` to `la` if they are not there already.
  
      The elements added to `la` maintain ordering with respect to `lb`.
  
      Args:
        la: List of Python objects.
        lb: List of Python objects.
      Returns:
        `la`: The list `la` with missing elements from `lb`.
      """
      la_set = set(la)
      for l in lb:
          if l not in la_set:
              la.append(l)
              la_set.add(l)
      return la
  
imports: from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.util import object_identity
label_desc: Use image node_id 3 for calling a global function with example usage: concatenate_unique(la, lb) and returns: la