code: def _recursive_getitem(d, key):
      
      if key in d:
          return d
      else:
          for v in d.values():
              return _recursive_getitem(v, key)
          else:
              raise KeyError('Key not found: {}'.format(key))
docs: Descend into a dict of dicts to return the one that contains
      a given key. Every value in the dict must be another dict.