code: def __init__(self, iterable=None):
      self.end = end = []
      end += [None, end, end]  # sentinel node for doubly linked list
      self.map = {}  # key --> [key, prev, next]
      if iterable is not None:
          self |= iterable
  
file_path: nibabel/nibabel/externals/oset.py
imports: from collections.abc import MutableSet
label_desc: Use image node_id 1 to create a new OrderedSet object from inherited base classes: MutableSet with example: obj = OrderedSet(iterable)