class_docstr: Python class for ordered set.
  Code taken from https://github.com/buyalsky/ordered-hash-set/tree/5198b23e01faeac3f5398ab2c08cb013d14b3702.
code: def __init__(self, elements=None):
      self._set = {}
      self._start = None
      self._end = None
      if elements is not None:
          for element in elements:
              self.add(element)
  
file_path: dowhy/dowhy/utils/ordered_set.py
label_desc: Use image node_id 1 to create a new OrderedSet object  with example: obj = OrderedSet(elements)