docs: def merge_dicts(*args):
      r"""
      add / concatenate / union / join / merge / combine dictionaries
  
      Copies the first dictionary given and then repeatedly calls update using
      the rest of the dicts given in args. Duplicate keys will receive the last
      value specified the list of dictionaries.
  
      Returns:
          dict: mergedict_
  
      CommandLine:
          python -m utool.util_dict --test-merge_dicts
  
      References:
          http://stackoverflow.com/questions/38987/how-can-i-merge-two-python-dictionaries-in-a-single-expression
  
      Example:
          >>> # ENABLE_DOCTEST
          >>> from utool.util_dict import *  # NOQA
          >>> import utool as ut
          >>> x = {'a': 1, 'b': 2}
          >>> y = {'b': 3, 'c': 4}
          >>> mergedict_ = merge_dicts(x, y)
          >>> result = ut.repr4(mergedict_, sorted_=True, newlines=False)
          >>> print(result)
          {'a': 1, 'b': 3, 'c': 4}
  
      """
      iter_ = iter(args)
      mergedict_ = six.next(iter_).copy()
      for dict_ in iter_:
          mergedict_.update(dict_)
      return mergedict_